The Great Expedition Series, Book 21

A Million Whys: The Magnet Expedition for Curious Kids

By Crafty Clover. Published by Million Whys Press.

What Is a Magnetic Field, and Why Can’t We See It? Why Is Earth Like a Giant Bar Magnet? How Does a Fridge Door Stay Sealed Without a Latch? This book answers 150 questions like these, one question per page, each with a short video answer. Six expeditions: Invisible Pulls & Pushes, Magnet Magic & Materials, Earth’s Magnetic Shield, Finding the Way, Magnets at Work, and Animals, Planets & Magnet Safety.

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All 150 questions

Tap a question to watch its video and read the answer.

Expedition 1: Invisible Pulls & Pushes

1. What Is a Magnetic Field, and Why Can’t We See It?
2. Why Do Magnets Have Two Ends Called Poles?
3. Why Do Opposite Poles Attract but Matching Poles Push Apart?
4. What Happens If You Cut a Magnet in Half?
5. Why Is a Magnet’s Pull Strongest at Its Ends?
6. How Far Away Can a Magnet Reach?
7. Why Can a Magnet Work Through Paper, Water, and Even Your Hand?
8. What Are Magnetic Field Lines?
9. How Can Iron Filings Show the Shape of a Magnet’s Field?
10. How Can a Magnet Turn a Paper Clip Into a Tiny Magnet?
11. What Tiny Neighborhoods Inside Iron Decide If It Is a Magnet?
12. Why Do Some Magnets Lose Their Power Over Time?
13. What Is the Difference Between a Permanent Magnet and a Temporary Magnet?
14. How Do Scientists Measure How Strong a Magnet Is?
15. Why Do Two Magnets Seem to Jump Together at the Last Moment?
16. Why Does One Magnet Seem to Float Above Another?
17. Can a Magnet Have Only One Pole?
18. How Did the Poles of a Magnet Get the Names North and South?
19. How Is Magnetic Force Different From Gravity?
20. Why Does the Pull of a Magnet Get Stronger When It Is Closer?
21. Is Magnetism the Same as Electricity?
22. What Are the Strongest Magnets in the World?
23. Why Do Two Magnets Pushing Apart Feel Like Pressing on a Springy Cushion?
24. How Do Factories Make Magnets?
25. What Happens When You Bring a Magnet Near a Compass?

Expedition 2: Magnet Magic & Materials

26. Is All Stainless Steel Magnetic?
27. Why Do Magnets Stick to Some Coins but Not Others?
28. What Is Lodestone, the Natural Magnet?
29. Why Won’t Magnets Stick to Wood, Glass, or Plastic?
30. Why Do Magnets Cling to Steel Doors but Not to Walls?
31. How Can a Magnet Tell a Steel Can From an Aluminum Can?
32. Why Can a Magnet Pull Black Grains Out of Beach Sand?
33. Is There Really Iron in Breakfast Cereal?
34. Is Rust Magnetic?
35. What Is Ferrofluid, the Liquid That Grows Spikes?
36. Why Does a Magnet Stop Working When It Gets Very Hot?
37. Can Anything Block a Magnetic Field?
38. Why Do Flexible Fridge Magnets Have Stripes?
39. Is Everything a Little Bit Magnetic?
40. How Do Click-Together Magnetic Building Tiles Work?
41. How Do Magnetic Drawing Boards Work?
42. How Does Magnetic Putty Swallow a Magnet?
43. How Can You Find the Poles of a Magnet That Has No Label?
44. Why Does a Magnet Stick Harder to Thick Steel than to Thin Steel?
45. How Can a Magnet Make a Paper Clip Hover in the Air?
46. Can Magnets Help Find Rocks That Fell From Space?
47. How Does a Magnet Sweeper Pick Up Scattered Nails?
48. Why Do Some Fridge Magnets Slide Down the Door?
49. Why Do Magnets Ignore Real Gold and Silver?
50. How Can You Sort a Mystery Pile of Objects with Only a Magnet?

Expedition 3: Earth’s Magnetic Shield

51. Why Is Earth Like a Giant Bar Magnet?
52. How Does Swirling Liquid Metal Deep Inside Earth Make a Magnet?
53. Why Does Earth’s Inner Core Stay Solid Even Though It Is So Hot?
54. What Does the Magnetic Shield Around Our Planet Do?
55. What Happens When the Solar Wind Hits Earth’s Magnetic Shield?
56. What Is the Magnetosphere?
57. Why Is Earth’s Magnetic Bubble Shaped Like a Comet?
58. Why Do Magnetic North and True North Point Different Ways?
59. Is the Magnetic North Pole Really Moving?
60. Which Scientists Track the Pole as It Travels?
61. Did the North and South Magnetic Poles Ever Swap Places?
62. How Do Cooled Lava Rocks Keep a Record of the Old Field?
63. What Tools Measure the Pull of Earth’s Magnet?
64. Why Is There a Weak Spot Over the South Atlantic Ocean?
65. What Would Life Be Like If Earth’s Shield Vanished?
66. Why Did Mars Lose Its Magnetic Field?
67. Do Other Planets Have Magnetic Fields?
68. Why Does Jupiter Have Such a Huge Magnetic Field?
69. Why Do Scientists Call the Sun a Giant Magnet?
70. What Are Sunspots, and What Do Magnets Have to Do with Them?
71. Why Do Compass Needles Wiggle During a Magnetic Storm?
72. Is Earth’s Magnet Stronger than a Fridge Magnet?
73. Could Astronauts Use a Compass on the Moon?
74. Why Does a Hanging Magnet Tilt Downward Near the Poles?
75. Is Earth’s Magnetism the Same Strength Everywhere?

Expedition 4: Finding the Way

76. How Did People First Discover the Compass?
77. What Do the Letters and Numbers on a Compass Mean?
78. Why Is the Needle in Many Compasses Floating in Liquid?
79. How Can You Walk in a Straight Line Using a Compass?
80. What Can Fool a Compass?
81. How Can You Build a Simple Compass at Home?
82. Do Compasses Work the Same in the Southern Hemisphere?
83. How Did Sailors Steer Before GPS?
84. Why Do Iron Ships Need Compass Corrections?
85. How Does a Gyrocompass Find North Without a Magnet?
86. Why Do We Still Need Compasses When We Have GPS?
87. What Is Orienteering?
88. Why Does a Phone Ask You to Draw a Figure Eight to Fix Its Compass?
89. Can a Compass Work Underwater?
90. What Is a Compass Rose on a Map?
91. How Do Pilots Use Compass Headings, and Why Do Runways Have Numbers?
92. How Do People Find Their Way in the Arctic When Compasses Wobble?
93. Does Moss Really Grow Only on the North Side of Trees?
94. How Did Pacific Wayfinders Cross Oceans Without a Compass?
95. Why Do Most Maps Put North at the Top?
96. What Should You Do If You Get Lost on a Trail?
97. How Can a Watch and the Sun Show You Which Way Is South?
98. What Is Dead Reckoning?
99. How Do Geocachers Use Coordinates to Find Hidden Treasure?
100. How Can Sunrise and Sunset Help You Find Directions?

Expedition 5: Magnets at Work

101. How Does a Fridge Door Stay Sealed Without a Latch?
102. How Do Cabinet Doors Click Shut with Magnets?
103. How Does an Electromagnet Switch on and Off?
104. How Does a Giant Magnet Lift Cars and Scrap Steel?
105. How Do Magnets Help an Electric Motor Spin?
106. How Can Spinning a Magnet Make Electricity?
107. Why Must Metal Stay Out of the Room with an Mri Machine?
108. How Do the Stripes on Some Cards Store Information?
109. How Do Tapes and Hard Drives Store Information with Magnets?
110. How Does a Magnet Help a Window Alarm Know When It Opens?
111. How Does a Bike Computer Count Wheel Turns?
112. How Can a Train Float on Magnets?
113. How Can Magnets Slow Down a Roller Coaster Without Touching It?
114. Why Does a Magnet Fall Slowly Through a Copper Pipe?
115. How Can a Cooktop Heat a Pot Without a Flame?
116. How Can a Fire Door Stay Open and Still Close by Itself?
117. How Can a Lamp or Globe Float Above Its Base?
118. How Do Metal Detectors Find Hidden Metal?
119. How Does a Laptop Know When Its Lid Closes?
120. Why Is Some Money Printed with Magnetic Ink?
121. How Do Pinball Flippers Flick the Ball?
122. How Does an Electric Guitar Turn Plucked Strings Into Sound?
123. Why Can a Spinning Top Float Above a Magnetic Base?
124. How Do Food Factories Catch Stray Bits of Metal?
125. How Do Toy Train Cars Link Up with Magnets?

Expedition 6: Animals, Planets & Magnet Safety

126. How Do Sea Turtles Use Earth’s Magnet to Find Their Way?
127. Do Birds Really Have a Built-In Compass?
128. Can Sharks Use a Magnetic Map to Swim Home?
129. How Might Salmon Use Earth’s Magnet to Return to Their Home River?
130. Do Cows and Deer Really Face North and South?
131. Which Tiny Living Things Carry Their Own Compass Needles?
132. How Do Spiny Lobsters Use a Magnetic Map?
133. How Do Monarch Butterflies Use a Magnetic Compass?
134. Why Don’t Our Bodies Sense Magnets the Way They Sense Heat?
135. How Do Mole-Rats Use Magnetism Underground?
136. How Do Scientists Test Whether an Animal Can Sense Magnetism?
137. Could Bees or Ants Use Magnetism to Find Their Way?
138. What Is a Magnetar?
139. Why Do Mars Rovers Carry Magnets?
140. Do Magnets Work on the Space Station?
141. How Do Satellites Use Magnets to Turn Without Fuel?
142. Do Auroras Glow on Jupiter and Saturn Too?
143. Why Are Small Magnets Dangerous If Swallowed?
144. Why Should You Keep Strong Magnets Away From Phones and Bank Cards?
145. Why Can Strong Magnets Pinch Fingers and Shatter?
146. Why Must Some People Stay Away From Strong Magnets?
147. How Should You Store Magnets?
148. How Can You Tell If a Magnet Toy Is a Safe Choice?
149. What Are the Safe Rules for Magnet Experiments?
150. What Magnet Mysteries Are Scientists Still Trying to Solve?