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Energy and magnet questions for kids
Here are 338 questions about energy, electricity and magnets from 19 A Million Whys books, each with a short video answer. Book 21, The Magnet Expedition, Book 22, The Energy Expedition are all about energy, electricity and magnets, and the rest come from other books in the series. Tap any question to watch the video and read the answer.
From Book 21: The Magnet Expedition (150)
What Is a Magnetic Field, and Why Can’t We See It?
A magnetic field is the invisible space around a magnet where its push and pull can reach. You cannot see it, because it is not made of light or of anything you can touch.
Why Do Magnets Have Two Ends Called Poles?
Every magnet has two poles, called north and south. They are the places where its pulling power is strongest.
Why Do Opposite Poles Attract but Matching Poles Push Apart?
Opposite poles pull together, but matching poles push apart. The secret is in the direction of a magnet's field.
What Happens If You Cut a Magnet in Half?
If you cut a magnet in half, you do not get a north piece and a south piece. You get two smaller magnets, and each one has its own north and south pole!
Why Is a Magnet’s Pull Strongest at Its Ends?
A bar magnet pulls hardest at its two ends and weakest in its middle. That happens because of what the tiny groups inside are doing.
How Far Away Can a Magnet Reach?
A magnet's field never stops all at once, but it fades very quickly with distance. A small fridge magnet might only reach a paper clip a few inches away.
Why Can a Magnet Work Through Paper, Water, and Even Your Hand?
A magnetic field passes right through most things that are not magnetic. That includes paper, plastic, wood, glass, water, and even your skin.
What Are Magnetic Field Lines?
Magnetic field lines are imaginary curved lines that scientists draw. They show the shape and direction of a magnetic field.
How Can Iron Filings Show the Shape of a Magnet’s Field?
Iron filings are tiny slivers of iron, like very fine metal dust. Around a magnet, they line up to draw the shape of its field.
How Can a Magnet Turn a Paper Clip Into a Tiny Magnet?
Paper clips are steel, and steel has iron in it. Next to a magnet, it can become a tiny magnet itself!
What Tiny Neighborhoods Inside Iron Decide If It Is a Magnet?
Inside a piece of iron are tiny neighborhoods called domains. Each domain holds millions of atoms that all point their magnetic directions the same way.
Why Do Some Magnets Lose Their Power Over Time?
Magnets do not last forever. A magnet gets weaker when the domains inside it get scrambled.
What Is the Difference Between a Permanent Magnet and a Temporary Magnet?
A permanent magnet keeps its magnetism for a long time. A temporary magnet acts like a magnet only while another magnet is nearby.
How Do Scientists Measure How Strong a Magnet Is?
Scientists have special tools that measure how strong a magnetic field is. They read the strength in units called gauss or tesla.
Why Do Two Magnets Seem to Jump Together at the Last Moment?
Have you ever felt two magnets jump together at the last moment? A magnet's pull grows stronger very quickly as the magnets get closer.
Why Does One Magnet Seem to Float Above Another?
When you stack ring magnets with matching poles facing, the top one seems to float! The magnets push each other apart, and that push holds the top one up.
Can a Magnet Have Only One Pole?
So far, no one has ever found a magnet with just one pole. Every magnet ever made or found has both a north and a south pole.
How Did the Poles of a Magnet Get the Names North and South?
The names north pole and south pole come from how a magnet points on Earth. Long ago, people noticed something about a magnet that could swing freely.
How Is Magnetic Force Different From Gravity?
Magnetic force and gravity are both invisible forces, but they act in different ways. Gravity only pulls, while magnetism can pull or push.
Why Does the Pull of a Magnet Get Stronger When It Is Closer?
A magnet pulls harder when it is closer for the same reason a flashlight looks brighter up close. Magnetic fields spread out in all directions as they leave the poles.
Is Magnetism the Same as Electricity?
Magnetism and electricity are two sides of one force, called electromagnetism. They are closely connected, but they are not the same thing.
What Are the Strongest Magnets in the World?
Some magnets are small enough to fit in your hand, and some are as big as a room. The strongest everyday magnets are made of neodymium, iron, and boron.
Why Do Two Magnets Pushing Apart Feel Like Pressing on a Springy Cushion?
Push two magnets together with matching poles facing, and something strange happens. It feels like you are pressing on a springy cushion, even though nothing is touching!
How Do Factories Make Magnets?
Magnets are made in factories, and the recipe starts with metal. Workers pour, press, and shape the metal into the form they want.
What Happens When You Bring a Magnet Near a Compass?
A compass needle is a small magnet that can spin freely. It points along the strongest magnetic field nearby.
Is All Stainless Steel Magnetic?
Is stainless steel always magnetic? No!
Why Do Magnets Stick to Some Coins but Not Others?
Take a magnet and test a handful of coins, and you may get a surprise. Some coins stick, some do not, and some stick just a little.
What Is Lodestone, the Natural Magnet?
Long ago, people found strange rocks in the ground that could attract iron. We call them lodestones, and they are natural magnets.
Why Won’t Magnets Stick to Wood, Glass, or Plastic?
Magnets are picky. They stick to only a few kinds of materials.
Why Do Magnets Cling to Steel Doors but Not to Walls?
Magnets love to cling to a steel fridge door, but they will not cling to a wall. A fridge door usually has a thin steel layer hiding under its paint or plastic.
How Can a Magnet Tell a Steel Can From an Aluminum Can?
A magnet can sort cans without even looking at them. Food cans are usually steel, and many soda cans are aluminum.
Why Can a Magnet Pull Black Grains Out of Beach Sand?
Walk along some beaches and you might spot dark streaks in the sand. Those streaks hide tiny black grains that a magnet can pull right out.
Is There Really Iron in Breakfast Cereal?
Many breakfast cereals are fortified, which means iron was added to them. The iron helps people stay healthy, and it is mixed in as a fine metal powder.
Is Rust Magnetic?
Is rust magnetic? Ordinary rust is a reddish iron oxide, and it is only very weakly magnetic.
What Is Ferrofluid, the Liquid That Grows Spikes?
Ferrofluid is a strange liquid that grows spikes when a magnet comes near. It is full of magnetic particles so tiny that they float like dust in sunlight.
Why Does a Magnet Stop Working When It Gets Very Hot?
Heat can make a strong magnet stop working. When atoms get hot, they jiggle faster and faster.
Can Anything Block a Magnetic Field?
Is there any way to block a magnetic field? Nothing blocks it completely, but some materials can redirect it.
Why Do Flexible Fridge Magnets Have Stripes?
Flexible fridge magnets have a secret hidden inside them. They are made of rubber mixed with magnetic powder, and they are magnetized in thin stripes.
Is Everything a Little Bit Magnetic?
Is everything a little bit magnetic? In a way, yes!
How Do Click-Together Magnetic Building Tiles Work?
Click-together magnetic tiles snap into shapes and come apart with a flip. Hidden inside each tile are small magnets, set in a pattern.
How Do Magnetic Drawing Boards Work?
A magnetic drawing board lets you draw a picture and erase it with one swipe. It looks like magic, but it is really a clever trick with magnets and tiny cells of powder.
How Does Magnetic Putty Swallow a Magnet?
Magnetic putty seems to gobble up a magnet, like a very slow monster. It is a stretchy putty that is mixed with fine iron powder.
How Can You Find the Poles of a Magnet That Has No Label?
Imagine you find a magnet with no label at all, and you need to know which end is north. A compass can solve the mystery.
Why Does a Magnet Stick Harder to Thick Steel than to Thin Steel?
A magnet sticks harder to a thick piece of steel than to a thin one. It all comes down to how much magnetic field the steel can carry.
How Can a Magnet Make a Paper Clip Hover in the Air?
Can a paper clip hover in the air, held up by an invisible pull? Yes, with a thread, a magnet, and a little patience.
Can Magnets Help Find Rocks That Fell From Space?
Some rocks fall from space, and they are called meteorites. Many of them contain iron and nickel, which means a magnet may help find them.
How Does a Magnet Sweeper Pick Up Scattered Nails?
Imagine a workshop floor covered in sharp nails, tacks, and screws. A magnet sweeper can clean it up, with no pricked fingers at all.
Why Do Some Fridge Magnets Slide Down the Door?
Have you ever seen a fridge magnet slowly slide down the door? A fridge magnet pulls straight into the door, but gravity pulls it straight down.
Why Do Magnets Ignore Real Gold and Silver?
Gold and silver are beautiful, but magnets just ignore them. These shiny metals are not magnetic at all.
How Can You Sort a Mystery Pile of Objects with Only a Magnet?
You have a mystery pile of small objects, and only a magnet to sort them. A magnet is a great tool for splitting any pile into two groups.
Why Is Earth Like a Giant Bar Magnet?
Earth has a magnetic field that looks a lot like the field around a giant bar magnet. It has a north end and a south end, and it reaches every place on the planet.
How Does Swirling Liquid Metal Deep Inside Earth Make a Magnet?
Deep under your feet, a layer of melted metal swirls around and around. That swirling is what makes Earth's magnetic field.
Why Does Earth’s Inner Core Stay Solid Even Though It Is So Hot?
At the very center of Earth sits a ball of iron and nickel as hot as the surface of the Sun. Even so, it is solid!
What Does the Magnetic Shield Around Our Planet Do?
Our planet has an invisible shield wrapped all around it. It is Earth's magnetic field, and it protects us from a stream of particles flying out from the Sun.
What Happens When the Solar Wind Hits Earth’s Magnetic Shield?
The Sun is always blowing a wind of tiny charged particles out into space. It is called the solar wind, and it blasts past Earth all the time.
What Is the Magnetosphere?
Earth's magnetic field does more than point your compass north. It builds a huge bubble in space, and our planet sits right in the middle.
Why Is Earth’s Magnetic Bubble Shaped Like a Comet?
Earth's magnetic bubble is not round like a ball. It is squeezed on one side and stretched on the other, a bit like a comet.
Why Do Magnetic North and True North Point Different Ways?
A compass needle does not point exactly to the North Pole. It points toward a different spot, called magnetic north.
Is the Magnetic North Pole Really Moving?
Earth's magnetic north pole is not staying still. It wanders across the Arctic year after year.
Which Scientists Track the Pole as It Travels?
Because the magnetic poles keep moving, someone has to keep track of them. Teams of scientists around the world do exactly that.
Did the North and South Magnetic Poles Ever Swap Places?
Here is a surprising fact: Earth's north and south magnetic poles have swapped places before! Rocks tell us it has happened hundreds of times in the past, though at irregular times.
How Do Cooled Lava Rocks Keep a Record of the Old Field?
Rocks can remember! When lava cools, tiny magnetic grains in it line up with Earth's field at that moment.
What Tools Measure the Pull of Earth’s Magnet?
How do scientists measure the pull of Earth's magnet? They use special sensors called magnetometers.
Why Is There a Weak Spot Over the South Atlantic Ocean?
Earth's magnetic field is strong in some places and weak in others. Over South America and the South Atlantic Ocean, it is weaker than almost anywhere else.
What Would Life Be Like If Earth’s Shield Vanished?
Imagine waking up one morning, and Earth's magnetic shield was gone. What would happen to life on Earth?
Why Did Mars Lose Its Magnetic Field?
Mars once had a magnetic field, a bit like Earth's. Today it is gone.
Do Other Planets Have Magnetic Fields?
Does Earth have the only magnetic field in space? Not at all!
Why Does Jupiter Have Such a Huge Magnetic Field?
Jupiter has the most powerful magnetic field of any planet. Its magnetic bubble is so huge that, if we could see it from Earth, it would look bigger than the full Moon!
Why Do Scientists Call the Sun a Giant Magnet?
We usually think of the Sun as a ball of fire and light. Scientists also call it a giant magnet!
What Are Sunspots, and What Do Magnets Have to Do with Them?
Some days, the Sun has dark patches on its surface called sunspots. They look like tiny freckles, but some are bigger than Earth!
Why Do Compass Needles Wiggle During a Magnetic Storm?
Sometimes the Sun throws out a giant burst of charged particles. When they hit Earth's magnetic field, they shake it, and that can make a compass needle wiggle.
Is Earth’s Magnet Stronger than a Fridge Magnet?
Which is stronger, the magnet in your hand or the magnet under your feet? The answer is a surprise.
Could Astronauts Use a Compass on the Moon?
Imagine walking on the Moon with a compass in your hand. Which way would the needle point?
Why Does a Hanging Magnet Tilt Downward Near the Poles?
Earth's magnetic field lines do not just run across the ground. Near the poles, they dive straight down into the planet!
Is Earth’s Magnetism the Same Strength Everywhere?
Earth's magnetic field is not the same strength everywhere you go. It is stronger in some places and weaker in others.
How Did People First Discover the Compass?
The compass is one of the greatest tools ever invented. But nobody knows the exact day it was discovered.
What Do the Letters and Numbers on a Compass Mean?
A compass is covered with letters and numbers. They are not decorations, they are a secret code for finding your way.
Why Is the Needle in Many Compasses Floating in Liquid?
Look closely at many compasses, and you will see something strange. The needle floats in a clear liquid!
How Can You Walk in a Straight Line Using a Compass?
Have you ever tried to walk in a straight line without a path? It is much harder than you think!
What Can Fool a Compass?
A compass seems simple, but lots of things can fool it. Anything magnetic, or any electric current nearby, can pull on a compass needle.
How Can You Build a Simple Compass at Home?
You can build your very own compass at home with just a few simple things. All you need is a steel pin or paper clip, a magnet, and a bowl of water.
Do Compasses Work the Same in the Southern Hemisphere?
Does a compass work the same way in the Southern Hemisphere? Yes, it still points toward magnetic north!
How Did Sailors Steer Before GPS?
Long ago, sailors crossed whole oceans without GPS. They did it by combining many simple tools, and a lot of careful thinking.
Why Do Iron Ships Need Compass Corrections?
Big iron and steel ships have a problem with compasses. The ship itself becomes a little magnetic, and that fools the needle!
How Does a Gyrocompass Find North Without a Magnet?
Is there a compass that works without any magnet at all? Yes!
Why Do We Still Need Compasses When We Have GPS?
GPS is amazing, but it does not always work. So smart hikers still carry a compass.
What Is Orienteering?
Imagine a race where your map and compass matter as much as your legs. That is orienteering!
Why Does a Phone Ask You to Draw a Figure Eight to Fix Its Compass?
Sometimes a phone asks you to wave it in a figure eight to fix its compass. It might seem like a silly dance.
Can a Compass Work Underwater?
Can a compass really work underwater? It sounds tricky, because water changes so many things.
What Is a Compass Rose on a Map?
Look at a map, and you may see a pretty little star or flower in one corner. That is a compass rose!
How Do Pilots Use Compass Headings, and Why Do Runways Have Numbers?
When pilots fly, they need to know exactly which way to go. They use compass headings, and airports even put those numbers on the runways!
How Do People Find Their Way in the Arctic When Compasses Wobble?
The Arctic is a land of ice and snow, and it is also close to the magnetic north pole. That makes a regular compass act strangely.
Does Moss Really Grow Only on the North Side of Trees?
You might have heard that moss grows only on the north side of trees. Is it true?
How Did Pacific Wayfinders Cross Oceans Without a Compass?
Thousands of years ago, brave sailors crossed huge oceans in canoes. They had no compasses, and no maps, and yet they found tiny islands in the Pacific.
Why Do Most Maps Put North at the Top?
Look at almost any map, and north is at the top. But there is no law of nature that says it has to be!
What Should You Do If You Get Lost on a Trail?
Getting lost on a trail can feel scary. But if you know the right steps, you can stay safe.
How Can a Watch and the Sun Show You Which Way Is South?
Here is a cool trick for finding south with nothing but a watch and the Sun. It works in the Northern Hemisphere with an old-style watch that has hands.
What Is Dead Reckoning?
Imagine you are lost at sea, with no GPS and no landmarks anywhere. How could you figure out where you are?
How Do Geocachers Use Coordinates to Find Hidden Treasure?
Imagine a treasure hunt where the treasure is hidden somewhere in the real world. It is called geocaching, and people play it all over the globe.
How Can Sunrise and Sunset Help You Find Directions?
The Sun can be a natural compass. It rises in one place and sets in another.
How Does a Fridge Door Stay Sealed Without a Latch?
Have you ever noticed that a fridge door closes tight without any latch or lock? The secret is a magnet hidden in the rubber seal around the edge.
How Do Cabinet Doors Click Shut with Magnets?
Push a cabinet door almost closed, and it clicks shut all by itself. There is no spring, no hook, and no latch.
How Does an Electromagnet Switch on and Off?
Imagine a magnet you can switch on and off, like a light. It is called an electromagnet!
How Does a Giant Magnet Lift Cars and Scrap Steel?
At a scrap yard, a giant crane lifts a huge pile of steel with no hooks or ropes around it. It uses a giant electromagnet instead.
How Do Magnets Help an Electric Motor Spin?
Inside a fan, a toy car, or even your phone, a small motor is spinning. And magnets are the secret to how it works.
How Can Spinning a Magnet Make Electricity?
A spinning magnet can make electricity! That is how most of the power that lights your home gets made.
Why Must Metal Stay Out of the Room with an Mri Machine?
In a hospital, there is a room with a very special rule: no metal allowed! It holds an MRI machine, with one of the strongest magnets people have ever used in a hospital.
How Do the Stripes on Some Cards Store Information?
Turn over a gift card or a hotel key card, and you might see a dark stripe. It looks like plain brown tape, but it hides a secret code made from tiny magnets.
How Do Tapes and Hard Drives Store Information with Magnets?
Old cassette tapes and computer hard drives look very different. But they share a secret: both store information using tiny magnetic patterns.
How Does a Magnet Help a Window Alarm Know When It Opens?
A window alarm can tell the moment a window opens, even though it has no eyes. The secret is a magnet and a tiny glass switch.
How Does a Bike Computer Count Wheel Turns?
A bike computer can tell you how fast you are going and how far you have ridden. But it never touches the wheel!
How Can a Train Float on Magnets?
Imagine a train that floats just above its track, with no wheels touching at all. It is called a maglev train, and it really exists!
How Can Magnets Slow Down a Roller Coaster Without Touching It?
At the end of some roller coasters, the cars slow to a smooth stop without anything touching them. The secret is magnets!
Why Does a Magnet Fall Slowly Through a Copper Pipe?
Drop a magnet through a plastic pipe, and it falls fast. Drop it through a copper pipe, and it falls slowly, as if something invisible is catching it!
How Can a Cooktop Heat a Pot Without a Flame?
Some stoves can cook your dinner without a single flame. They use an invisible magnetic field to heat the pot.
How Can a Fire Door Stay Open and Still Close by Itself?
In some school hallways, heavy fire doors stay wide open all day. But when there is a fire alarm, they swing closed all by themselves!
How Can a Lamp or Globe Float Above Its Base?
In some shops and homes, a lamp or a globe floats in the air above its base. It seems like magic, but it is really clever engineering.
How Do Metal Detectors Find Hidden Metal?
Metal detectors can find coins, keys, and treasure hidden under sand or soil. They work with an invisible magnetic field.
How Does a Laptop Know When Its Lid Closes?
Close your laptop, and the screen turns off at once. Open it, and the laptop wakes up.
Why Is Some Money Printed with Magnetic Ink?
Some paper money and bank checks have a secret ingredient in their ink: tiny magnetic particles! You cannot see the magnetism, but machines can sense it.
How Do Pinball Flippers Flick the Ball?
Press the button on a pinball machine, and the flipper snaps up in a flash. Inside, an electromagnet is hard at work, even though you cannot see it.
How Does an Electric Guitar Turn Plucked Strings Into Sound?
An electric guitar does not have a big hollow body to make its sound louder. Instead, it has magnets and thin wire hiding under the strings.
Why Can a Spinning Top Float Above a Magnetic Base?
Some toys have a spinning top that floats in the air above a magnetic base. It seems to defy gravity!
How Do Food Factories Catch Stray Bits of Metal?
Food factories work hard to keep every bite safe. Sometimes a tiny bit of metal, like a screw end or a wire piece, breaks off a machine.
How Do Toy Train Cars Link Up with Magnets?
Wooden toy trains can link together without any hooks or buckles. The secret is hidden magnets in the ends of each car.
How Do Sea Turtles Use Earth’s Magnet to Find Their Way?
A baby sea turtle hatches on a beach, swims out to sea, and years later returns to lay its eggs on the very same beach. How does it find its way across a huge ocean?
Do Birds Really Have a Built-In Compass?
Every year, many birds fly thousands of miles to warmer places and then back again. They do not use maps or GPS.
Can Sharks Use a Magnetic Map to Swim Home?
Sharks swim across huge oceans and somehow find their way home. Scientists wondered if they might use a magnetic map.
How Might Salmon Use Earth’s Magnet to Return to Their Home River?
Salmon begin their lives in a small river. They swim out to the ocean for years, and then return to the very same river where they were born.
Do Cows and Deer Really Face North and South?
In 2008, some scientists made a surprising claim. They said cows and deer might line up north and south when they graze or rest.
Which Tiny Living Things Carry Their Own Compass Needles?
Some of the tiniest living things on Earth carry their own compass needles. They are so small that you need a powerful microscope to see them.
How Do Spiny Lobsters Use a Magnetic Map?
Spiny lobsters can crawl a long way across the ocean floor and still find their way home. They do not have eyes that work in the dark depths.
How Do Monarch Butterflies Use a Magnetic Compass?
Every fall, monarch butterflies fly thousands of miles to Mexico. Even though they are tiny, they find their way to the very same forests.
Why Don’t Our Bodies Sense Magnets the Way They Sense Heat?
Birds, turtles, and sharks seem to sense magnets. But can you feel a magnet from far away?
How Do Mole-Rats Use Magnetism Underground?
Deep underground, there are animals that live in total darkness. Ansell's mole-rats in Africa live in dark tunnels and have very poor eyesight.
How Do Scientists Test Whether an Animal Can Sense Magnetism?
How can a scientist find out whether an animal can sense magnetism? The animal cannot tell us, so scientists must be clever.
Could Bees or Ants Use Magnetism to Find Their Way?
Honeybees and ants are tiny, but they are great at finding their way home. Could magnetism be part of their secret?
What Is a Magnetar?
Far out in space, there is a star with the strongest magnetic field anyone has ever found. It is called a magnetar.
Why Do Mars Rovers Carry Magnets?
Robots on Mars have carried small magnets, and it was not to stick things on a fridge. They used the magnets to catch dust from the air.
Do Magnets Work on the Space Station?
Do magnets still work when you float far above the ground in space? Yes, they do!
How Do Satellites Use Magnets to Turn Without Fuel?
How do you turn a satellite in space, where there is nothing to push against? One answer is magnets!
Do Auroras Glow on Jupiter and Saturn Too?
You may have heard of the auroras on Earth, the colorful northern and southern lights. But they are not only on Earth!
Why Are Small Magnets Dangerous If Swallowed?
Small magnets are fun to play with, but they have a dangerous side. If you swallow them, they can hurt you.
Why Should You Keep Strong Magnets Away From Phones and Bank Cards?
Strong magnets are amazing, but they do not belong next to your favorite gadgets. A magnet can scramble a bank card or confuse a phone.
Why Can Strong Magnets Pinch Fingers and Shatter?
Super-strong neodymium magnets are not toys. They can pinch a finger badly, and they can even shatter like glass.
Why Must Some People Stay Away From Strong Magnets?
Some people have special medical devices inside their bodies that help them stay healthy. Strong magnets can affect those devices.
How Should You Store Magnets?
You have learned lots of cool things about magnets. Now here is how to take care of them.
How Can You Tell If a Magnet Toy Is a Safe Choice?
Magnet toys can be great fun, but not every magnet toy is right for every age. How can you tell if one is a safe choice?
What Are the Safe Rules for Magnet Experiments?
Magnet experiments are great fun, and they are safe when you follow the rules. Think of the rules as the science lab's safety net.
What Magnet Mysteries Are Scientists Still Trying to Solve?
You have learned a lot about magnets in this journey. But scientists still have big magnet mysteries to solve.
From Book 22: The Energy Expedition (150)
What Exactly Is Energy?
Energy is the ability to make something change or move. It is what lets a ball roll, a plant grow, a bulb glow, and a kid run.
How Can You Tell Energy Is There When You Can’t See It?
Energy is never seen on its own. It is a bit like wind, which you only see in the leaves it moves.
What Kinds of Energy Are There?
Energy comes in many forms. Moving things, hot things, light, sound, and electricity are all energy.
How Is Stored Energy Different From Moving Energy?
Stored energy is energy that is waiting to be used. Moving energy is energy that is happening right now.
Why Can Energy Never Be Made or Destroyed?
Scientists have tested this for more than a hundred and fifty years. Energy is never made from nothing, and it never disappears.
Where Does a Ball’s Energy Go When It Stops Rolling?
A rolling ball slowly slows down and stops. But the ball's energy does not simply disappear.
What Does It Mean to “Use Up” Energy?
People often say they use up energy. But energy never really vanishes.
Why Does a Stretched Rubber Band Hold Energy?
A stretched rubber band can fling a paper ball across a room. That is because stretching stores energy.
Why Does a Book on a High Shelf Hold Energy?
A book sitting on a high shelf looks very still. But it is secretly holding energy!
What Is the Energy Hiding in Food, Fuel, and Batteries?
Food, fuel, and batteries all have energy hiding inside. It is called chemical energy.
Why Do Scientists Call Heat Energy on the Move?
Heat is energy that moves from a warmer thing to a cooler thing. That is why scientists call it energy on the move.
How Does Energy Change From One Form Into Another?
Energy changes form whenever something happens. A toaster, a battery, a plant, and your muscles all do it.
How Can You Follow Energy From the Sun to Your Toast?
The toast on your plate holds energy that started in the Sun. Sunlight traveled a very long way to get there.
Why Do Machines Waste Some Energy?
In every machine, some energy turns into heat that nobody wanted. Engineers call that wasted energy.
What Does “Work” Mean in Science?
In everyday talk, work means a job or a task. But in science, work has a special meaning.
What Is Power, and How Is It Different From Energy?
Energy is the total amount, and power is how fast energy is used. Two people can use the same energy at different speeds.
How Do We Count Energy?
Energy can be counted with several different units. Scientists, food labels, and electric companies each choose their own.
How Did James Joule Show That Motion Can Turn Into Heat?
Long ago, a scientist named James Joule had a big question. Could motion turn into heat?
Do Rocks and Mountains Have Energy?
A rock sitting on the ground looks completely still. But does it have energy?
Why Do People Say “Save Energy” If Energy Never Disappears?
Energy never disappears, so why do people say save energy? It is because useful energy can run out.
What Happens to Energy When Two Things Bump?
Energy can hop from one thing to another when they bump. A moving ball, a warm hand, and even a sound all pass it along.
Why Does It Take Energy to Make Something Move, Even a Little?
A still object likes to stay still. To get it moving, you must give it some energy.
Is There Energy Inside Atoms?
Atoms are unbelievably tiny. But there is energy inside them in more than one way.
Can a Wave Carry Energy Without Carrying Stuff Along?
A wave carries energy from one place to another. But the stuff it moves through barely travels at all.
Why Can’t We Build a Machine That Runs Forever?
Imagine a machine that runs forever with no fuel at all. People have dreamed about it for hundreds of years.
What Is Kinetic Energy, the Energy of Motion?
Kinetic energy is the energy of motion. Anything that moves has it.
Why Does a Diver on a High Board Hold Potential Energy?
A diver on a high board is standing still. But she is holding a lot of energy!
Why Does Speed Matter So Much for Moving Energy?
A moving thing's energy grows fast with its speed. Double the speed, and the energy does not just double.
Why Does a Heavy Truck Have So Much More Moving Energy than a Bicycle?
A heavy truck and a bicycle can roll at the same speed. But the truck carries far more moving energy.
How Does a Roller Coaster Trade Height for Speed?
A roller coaster climbs a big hill very slowly. Then it zooms down at top speed!
Why Does a Pendulum Swing Back and Forth?
A pendulum is just a weight hanging from a string. Yet it swings back and forth in a steady rhythm.
Why Does a Ball Speed Up Faster on a Steeper Hill?
A ball rolling down a steep hill speeds up fast. On a gentle hill, it speeds up slowly.
Where Does a Squashed Spring’s Stored Energy Go When You Let Go?
Squeezing or stretching a spring puts energy into it. Let go, and it springs right back!
How Does a Wind-Up Toy Store Energy?
A wind-up toy walks, hops, or rolls without a battery. The secret is a twisted metal spring inside.
Why Does Falling From Higher Up Hurt More?
Falling from higher up hurts more than falling from low. Energy is the reason.
How Does a Moving Bowling Ball Pass Energy to the Pins?
A rolling bowling ball is full of moving energy. When it crashes into the pins, they fly everywhere.
Why Can One Domino Knock Over a Whole Row?
Line up lots of dominoes and tip the first one. Click, click, click, they all fall down!
Where Does the Energy Come From When You Jump?
When you jump, you go up in the air all by yourself. Where does the energy for that come from?
How Does a Toy Catapult Launch Things?
A toy catapult can toss a soft pom-pom across the room. It does that with stored energy.
How Does a Cyclist Use Energy to Climb a Hill and Then Coast?
Pedaling uphill is hard work. But coasting down feels like magic.
Where Does the Energy Go When Bike Brakes Stop You?
When you squeeze bike brakes, you slow down quickly. But the moving energy does not just vanish.
How Do Electric and Hybrid Cars Save Energy While Braking?
Most brakes turn a car's moving energy into wasted heat. But electric and hybrid cars have a clever trick.
How Does a Flywheel Store Energy?
A flywheel is just a heavy wheel that spins. Once it gets going, it just keeps on spinning.
How Does a Hand-Crank Flashlight Work Without Batteries?
A hand-crank flashlight has no batteries to replace. You just turn the crank, and the light comes on.
How Does a Yo-Yo Store Spinning Energy?
A yo-yo drops, spins, and climbs right back up your hand. The secret is spinning energy.
How Does a Balloon Rocket Use Stored Energy?
A blown-up balloon holds energy in the air inside it. Let it go, and it zooms around the room!
Why Does a Pogo Stick Make You Bounce?
A pogo stick lets you bounce up and down like a kangaroo. The secret is a strong spring.
How Does a Zipline Turn Height Into Speed?
A zipline sends riders gliding along a cable. They start high and end low.
Why Is a Heavy Box Harder to Push than an Empty One?
A heavy box is harder to push than an empty one. You may think it is only because it weighs more.
How Do Helmets and Padding Soak Up Moving Energy?
A helmet has soft foam inside. When something hits it, the foam squashes.
How Does the Sun’s Energy Cross Empty Space to Reach Us?
The space between the Sun and Earth is almost completely empty. There is no air to carry heat across it.
What Makes the Sun Give Off So Much Energy?
The Sun gives off an amazing amount of energy every single second. Where does it all come from?
How Much of the Sun’s Energy Does Earth Actually Catch?
The Sun sends its light out in every direction. Earth is a small target, far away.
How Can Heat Travel From Place to Place?
Heat does not stay in one place. It moves in three different ways.
Which Holds More Heat: a Cup of Hot Tea or a Tub of Warm Water?
Which holds more heat, a small cup of hot tea or a big tub of warm water? Most people guess the tea.
How Does a Blanket Keep You Warm If It Makes No Heat?
A blanket feels so warm and cozy. But a blanket makes no heat at all!
How Does a Leaf Turn Sunshine Into Food?
A green leaf is a tiny food factory. It runs on sunshine!
How Is a Solar Water Heater Different From a Solar Panel?
Rooftops can use the Sun in two different ways. One makes hot water, and the other makes electricity.
What Is Infrared Light?
Beyond the red light you can see, there is another kind of light. Your eyes cannot see it.
Why Does a Parked Car Get So Hot with the Windows Closed?
A parked car can get dangerously hot, even on a mild day. Sunlight gets in easily.
Why Do Very Hot Things Glow?
When something gets hot enough, it begins to glow. The hotter it gets, the more the color changes.
Why Does Sand Heat Up Faster than Water?
On a sunny beach, the sand feels scorching hot. But the water feels cool, even after the same hours of sun.
How Does the Sun’s Energy Keep Water Moving Around the Planet?
The Sun does not only light our days. It also keeps water moving around the whole planet.
What Invisible Rays Does the Sun Send Us?
Sunlight is more than the light we can see. It also carries invisible rays.
How Much Power Does Sunshine Bring to One Square Meter?
Sunshine brings real power to the ground. Let's measure how much lands on one square meter.
How Did People Long Ago Put Sunshine to Work?
People have used the Sun's energy for thousands of years. Long before electric power, they put sunshine to work.
How Much Power Does a Solar Panel Lose When Clouds Roll In?
Solar panels love sunshine. But clouds sometimes roll in and cover the sky.
How Does a Thermos Keep Soup Warm?
A thermos keeps soup hot for hours. It can also keep a cold drink cold.
How Does a Hot-Water Radiator Warm a Room?
A radiator can warm a whole room. It does it without any fan or blowing.
What Happens to Light When Something Swallows It?
When light hits something, it can bounce off or get swallowed. Swallowed light turns into heat.
What Are the Tiny Packets of Energy in a Sunbeam?
Light travels as a wave. But it also comes in tiny packets of energy called photons.
How Much Heat Does a Person Give Off?
Sitting still, your body is giving off heat. In fact, you are about as warm as a bright light bulb!
How Hot Is the Sun’s Surface, and How Hot Is Its Core?
The Sun is a ball of glowing gas. But different parts of it have wildly different temperatures.
How Do Astronauts Keep Cool in Space Where There Is No Air?
In space, there is no air at all. That means no breeze to cool an astronaut.
Why Doesn’t Earth Keep Getting Hotter If the Sun Keeps Sending Energy?
The Sun keeps sending energy to Earth every day. So why doesn't our planet keep getting hotter and hotter?
How Do Scientists Find Out How Much Energy Is in a Peanut?
How could anyone measure the energy in a peanut? Scientists use a clever device.
Why Is the Calorie on a Food Label Spelled with a Capital C?
Food labels list Calories. You may have noticed that the word starts with a capital C.
How Does Your Body Get Energy Out of Food?
Food has energy locked inside. Your body has to unlock it.
How Do Your Cells Burn Food Without Fire?
Your cells burn food, but there is no flame. There is no smoke or fire at all.
Why Does Your Body Make Its Own Heat?
Your body makes its own heat. That is why you stay warm even when it is chilly outside.
How Do Muscles Use Food Energy to Move?
Every time you lift a spoon or kick a ball, your muscles are working. And muscles run on food energy.
Why Do Small Animals Eat So Much for Their Size?
A tiny shrew eats almost all day long. An elephant eats a lot too, but far less for its size.
Why Do Reptiles Need Less Food than Mammals?
A lizard sunbathes on a warm rock. Snakes can go weeks between meals.
Where Does Energy Go as It Moves Up a Food Chain?
A rabbit eats grass, and a fox eats the rabbit. But energy gets smaller at every step.
Why Do Ecosystems Have So Many More Plants than Meat-Eaters?
A meadow has thousands of grasshoppers. But it has only a few hawks.
How Do Plants Store the Energy They Make?
Plants make sugar from sunshine. But they do not use it all at once.
What Makes Fat Such a Good Energy Bank?
Bears, birds, and many other animals pack on fat. They do it before winter or a long trip.
How Does Hibernating Save Energy?
In winter, food is hard to find. Some animals just go to sleep for months.
What Is Metabolism?
Even when you are fast asleep, your body is busy. All the chemistry that keeps you going has a name.
Where Does the Energy in Coal and Oil Come From?
Coal and oil are burned to make power. But where did their energy come from in the first place?
Why Does Burning Release Stored Energy?
Fire is amazing and dangerous. Fuels like wood and gasoline hold lots of energy inside them.
Why Do Liquid Fuels Pack So Much Energy?
A little liquid fuel can carry a huge amount of energy. Think of how far a tank of gasoline can take a car.
How Does a Car Engine Turn Fuel Into Motion?
Under a car's hood, small explosions happen again and again. They turn fuel into motion.
What Is Biofuel?
Some fuel does not come from deep underground. It comes from plants that are growing right now.
How Did People First Use Wood to Cook and Stay Warm?
People have burned wood for a very long time. They used it for cooking, for light, and for warmth.
How Can Rotting Food Scraps Make Fuel?
Banana peels and leftover scraps usually end up as trash. But rotting food can be turned into fuel!
How Can an Eel’s Body Make Electric Shocks?
An electric eel can give a real jolt. It is not a magic power.
Why Can a Cheetah Sprint Fast but Not for Long?
A cheetah is the fastest land animal on Earth. But it cannot run that fast for very long.
Why Do Migrating Birds Eat So Much Before a Long Trip?
Some birds fly across whole oceans without stopping to eat. That takes a lot of fuel.
How Do Deep-Sea Animals Get by with So Little Food?
The deep ocean is dark and cold. No sunlight reaches it, so no plants grow.
How Does a Power Plant Make Electricity for a Whole Town?
A power plant makes electricity for a whole town. The secret is a spinning machine.
What Is the Power Grid?
Electricity travels a long way to reach your home. It rides along a giant network of wires.
Why Do Long-Distance Power Lines Use Such High Voltage?
Big power lines carry electricity over long distances. They use very high voltage to do it.
Why Do Many Power Plants Burn Fuels Like Coal and Gas?
Many power plants burn coal, oil, or natural gas. It is a simple way to get a lot of heat.
What Makes an Energy Source Renewable?
Some energy sources keep coming back. Others run out.
How Does a Wind Turbine Turn Wind Into Electricity?
A giant wind turbine looks like a big pinwheel. It makes electricity from the wind.
Why Do Wind Farms Put Their Turbines So High Up?
Wind farms put their turbines way up high. They use tall towers and very long blades.
How Do Rooftop Solar Panels Share Power with the Grid?
Solar panels on a roof can power a home. But that is not all they do.
How Does a Tidal Power Station Use the Ocean?
The ocean rises and falls twice every day. That is the tide, and it has a lot of energy.
How Can Ocean Waves Make Electricity?
Ocean waves never stop moving. That motion is energy.
What Is Nuclear Energy, and How Does a Power Plant Use It?
Nuclear power plants do not burn anything. They get their heat by splitting atoms.
What Happens to Solar and Wind Power When the Sun Sets or the Wind Stops?
Solar panels make no power at night. Wind turbines slow down when the air is calm.
How Can We Store Extra Electricity?
Electricity is very hard to store directly. So we change it into another form of energy.
How Does Pumped Storage Work Like a Giant Water Battery?
Imagine a giant battery made of water. It uses two lakes, one high and one low.
What Is a Kilowatt-Hour on an Electricity Bill?
Your family's electricity bill has a strange unit on it. It says kilowatt-hours.
Why Does the Electricity in a Town Sometimes Go Out?
Sometimes the lights go out all at once. It can feel a bit spooky.
How Do Solar Lamps and Small Grids Bring Light to Faraway Places?
Some villages are far from any power line. Still, they can have light at night.
How Is an Electric Car Charged, and Where Does That Energy Come From?
An electric car has no gas tank. It runs on a big battery instead.
Can Hydrogen Be a Clean Fuel?
Hydrogen is a gas that can be a fuel. When it is used in a special device, the only leftover is water.
How Much Electricity Can You Make by Pedaling?
Could you power a light bulb with your own legs? A pedal generator can find out!
Why Do Solar Panels in Canada Face South?
Rooftop solar panels in Canada usually face south. That is not random.
What Is That Gray Can on the Power Pole?
Have you ever noticed a gray can on a power pole? It is not a trash can or a light.
Why Do Some Power Plants Have Giant Cooling Towers?
Some power plants have giant towers that look like huge vases. White clouds float up out of them.
Why Does Electricity Use Go Up in the Evening?
Every evening, people all come home at the same time. They flip on lights, cook dinner, and watch TV.
What Is the Trade-Off with Each Energy Source?
Every energy source has good points. And every one has challenges too.
What Does Energy Efficiency Mean?
Two light bulbs can glow just as bright. But one can use much less electricity.
What Do Energy Star and EnerGuide Labels Tell Us?
Fridges and washers often wear special labels. These labels tell you how much energy a machine uses.
Why Do Some Devices Use Power Even When They Are Turned Off?
Your TV looks like it is off. But a tiny red light is still glowing.
Why Do Windows Let So Much Heat Escape in Winter?
In winter, warmth tries to sneak out of your house. Windows are one of its favorite exits.
How Does Insulation Keep a House Cozy?
A cozy house in winter needs a warm blanket in the walls. It is made of tiny pockets of trapped air.
How Does a Thermostat Know When to Turn the Heat On?
A thermostat is like a little brain for your heating. It keeps your home at just the right temperature.
How Does a Heat Pump Move Heat Instead of Making It?
A heat pump does not make heat. It moves heat from one place to another.
Why Does Hanging Laundry Outside Save Energy?
A clothes dryer uses a lot of energy. A clothesline uses almost none at all.
What Happens If the Fridge Door Stays Open?
What if the fridge door stays open? Cold air rushes out into the kitchen.
Why Does Putting a Lid on a Pot Save Energy?
Cooking with the lid off lets heat slip away. Putting the lid on is an easy energy saver.
Does Taking a Shorter Shower Really Save Energy?
A shower feels wonderful on a cold morning. But heating all that water takes lots of energy.
How Can Trees Around a House Save Energy?
Trees can work like free air conditioners for a house. They also block cold winter wind.
What Is Passive Solar Design?
Some buildings are designed to catch the Sun's free heat. They do it with no machines at all.
Is Biking More Energy-Efficient than Driving?
A person on a bike zooms along using only muscles. A car burns lots of fuel to go the same distance.
How Can You Find Drafts in Your Home?
Drafts are sneaky little leaks of air in your home. Cold air gets in and warm air gets out.
Which Energy-Saving Habits Matter Most?
Some energy-saving habits save more than others. Little choices can add up!
How Do Motion-Sensor Lights Save Energy?
Some lights switch on all by themselves when you walk by. They are called motion-sensor lights.
Why Does a Phone Charger Feel Warm?
Touch a phone charger, and it feels a bit warm. That warmth tells a secret.
Why Does Recycling an Aluminum Can Save Energy?
A used soda can goes in the recycling bin. That little act saves a surprising amount of energy.
What New Energy Ideas Are Scientists Testing?
Scientists and engineers never stop testing new ideas. Some might power our world someday.
How Can Your Class Run an Energy-Saving Project?
Your class can become a team of energy detectives. You can find wasted energy at school.
Can Footsteps on a Special Floor Make Electricity?
Could your footsteps make electricity? Special floor tiles say yes, a little.
Which Things in a Home Use the Most Energy?
Your home uses energy in many ways. Some things use much more than others.
Why Do Small Energy Savings Add Up?
One light turned off saves only a little. But little savings can add up to big ones.
What Are the Big Ideas to Remember About Energy?
We have explored energy in so many ways. Let's gather the big ideas to remember.
From Book 1: The Great Expedition (4)
Why Is Lightning So Hot? Big Energy in a Tiny Strike!
Lightning is a giant electric current that races through the air in an extremely narrow channel. The page says that channel can reach about 30,000 degrees C (54,000 degrees F).
Why Do Magnets Stick? North, South and Tiny Iron Bits!
Magnets have a north pole and a south pole. Opposite poles pull together and the same poles push apart.
How Does a Battery Work? Chemical Energy to Electricity!
A battery stores chemical energy. Inside, two sides want to react, and that reaction pushes electrons through a wire as electricity, like the wire that lights a bulb in a simple circuit.
Why Do Balloons Stick to Your Hair? Static Electricity!
Rub a balloon on your hair and it clings like magic, but it is really static electricity. Rubbing moves tiny charges, so the hair and the balloon end up with opposite charges.
From Book 2: The Inside Expedition (2)
Why Does the Brain Use So Much Energy?
Your brain is small, but it is one hungry organ! Even though it is small, it uses a big share of your body's energy, because being ready to fire is expensive.
Why Do Kids Have So Much Energy?
Kids are always on the go, running, jumping, and playing. That is because a growing body burns fuel to move, learn, and grow, all at once.
From Book 3: The Built Expedition (6)
Why Do Batteries Die?
A battery stores energy in chemicals. When you use it, those chemicals change.
Why Do Magnets Stick?
A magnet makes an invisible field. Iron, nickel, and some steels feel that field and get pulled in.
Why Do Solar Panels Work?
A solar panel is a sandwich of special silicon. Light packets called photons knock electrons free, so they can flow as current.
Why Does Static Make Hair Stick Up?
Rubbing moves electrons from one thing to another. That leaves things with an electric charge.
Why Does a Compass Point North?
A compass needle is a tiny magnet that can spin freely. And guess what?
Why Do Magnets Pick Up Only Some Metals?
A magnet has an invisible field around it. Some metals have tiny mini-magnets inside that can line up with that field.
From Book 4: The Wild Expedition (1)
From Book 6: The Ocean Expedition (1)
From Book 7: The Weather Expedition (1)
From Book 10: The Body Expedition (1)
From Book 11: The Animal Expedition (1)
From Book 12: The Volcano Expedition (2)
From Book 13: The Light Expedition (3)
How Does a Solar-Powered Calculator Work Without a Battery?
A solar calculator works without a battery because it makes electricity from light! A solar cell gives off a tiny bit of electricity when light hits it.
Why Do Some Solar Power Plants Use Hundreds of Mirrors?
Some solar power plants use hundreds of mirrors to gather sunlight! The mirrors tilt to follow the Sun and aim at one spot on a tower.
Why Does a Flashlight Get Dimmer as Its Batteries Run Down?
A flashlight gets dimmer as its batteries run down because the battery is running out of energy! A fresh battery gives a strong push of electricity.
From Book 14: The Sound Expedition (1)
From Book 15: The Robot Expedition (6)
How Does a Robot Get the Energy to Move?
Most robots get their energy from batteries! A battery stores energy that can turn into electricity.
How Can a Magnet Tell a Robot Where Its Parts Are?
A magnet can tell a robot where its parts are, with a sensor that feels magnetism! The sensor is called a Hall sensor.
Why Does a Motor Spin When You Connect a Battery?
A motor spins because electricity can turn a coil of wire into a magnet! Other magnets nearby push and pull on it, and that makes the coil turn.
Why Do Robots Climb Wind Turbines and Tall Towers?
Robots climb wind turbines and towers to check them for cracks and damage! The blades are very tall, so checking them is hard work.
Why Do Robots Clean Solar Panels?
Dust and dirt on a solar panel block some sunlight, so the panel makes less electricity! Cleaning robots wipe the panels so more light gets through.
Why Do Robot Batteries Need Extra Care?
Robot batteries need extra care because they store a lot of energy in a small package! Handled properly, they are safe and useful.
From Book 16: The Desert Expedition (2)
Why Are Deserts Such Good Places for Solar Panels?
Deserts are great places for solar panels because they have strong sunshine, clear skies, and lots of open land! Solar panels turn light into electricity.
How Do Mirror Fields in the Desert Turn Sunlight Into Electricity?
Mirror fields turn sunlight into electricity by using heat to make steam! Hundreds or thousands of mirrors tilt to follow the Sun.
From Book 18: The Polar Expedition (3)
Where Do Polar Stations Get Their Electricity?
Most polar stations make electricity with generators that burn special fuel! Some also use sunshine and wind, when they can.
Why Do Batteries and Metal Act Strangely in Extreme Cold?
Extreme cold changes how things work, especially batteries and some materials! Cold slows the chemical reactions that make a battery work, just like cold honey flows slowly.
Why Do Compasses Go Haywire Near the Poles?
A compass points to Earth's magnetic poles, and those are not the same as the geographic poles! Near the magnetic North Pole, the needle can tilt and wander.
