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A final review comparing magnetism and static electricity in the real world.
What if you had a 'superpower' that let you move objects without ever touching them? You use this power every time you stick a drawing to the fridge or get a 'zap' from a doorknob!
Magnetism is an invisible force that pulls on certain metals, like iron and nickel. Every magnet has two ends called poles: a North () pole and a South () pole. If you put two magnets together, they follow a special rule: Opposites attract, and likes repel. This means and will pull together, but and will push apart. Magnetism is 'always on' and doesn't need you to do anything to make it work!
Let's see how magnetism works step-by-step: 1. Place a metal paperclip on a table. 2. Hold a magnet inches above it. 3. Slowly move the magnet closer. 4. Watch as the paperclip 'jumps' up to the magnet without you touching it!
Quick Check
If you have two magnets and try to push the North pole of one against the North pole of the other, what will happen?
Answer
They will repel, or push each other away.
Static electricity is a different kind of invisible force. It happens when certain materials rub together, like a balloon rubbing on a wool sweater. This rubbing creates a charge. Unlike magnets, which are usually made of metal, static electricity can happen with plastic, rubber, or even your hair! Static electricity is often temporary—it builds up and then 'discharges' or jumps away, sometimes creating a tiny spark.
How to create a static charge: 1. Take a rubber balloon and rub it quickly against your hair for seconds. 2. The friction (rubbing) moves tiny invisible charges from your hair to the balloon. 3. Pull the balloon away slowly and watch your hair reach out to touch it! 4. Try sticking the balloon to a wall; the static charge will hold it there.
Quick Check
What is the main action needed to 'wake up' static electricity?
Answer
Rubbing two objects together (friction).
To be a Force Detective, you must look for clues. Ask yourself: Clue 1: Did I have to rub the objects together? If yes, it's likely static electricity. Clue 2: Is the object made of metal? If it's a metal like iron, it's likely magnetism. Clue 3: Does the force last a long time? Magnets stay magnetic for years, but static electricity usually disappears quickly.
Imagine you have a mixture of salt and pepper on a plate. You want to lift the pepper without touching it. 1. You rub a plastic spoon on your sleeve. 2. You hold the spoon over the plate. 3. The pepper jumps up to the spoon, but the salt stays down. 4. Detective Conclusion: This is static electricity because you used a plastic spoon and rubbing (friction) to make it work!
Which force requires you to rub two objects together to make it work?
A detective finds a force pulling on a heavy iron nail. Which force is most likely acting?
True or False: Both magnetism and static electricity can move objects without touching them.
Review Tomorrow
Tomorrow, try to explain to a friend why a magnet doesn't need to be rubbed to work, but a balloon does.
Practice Activity
Find three items in your house. Predict if a magnet will pull them, then test it! Then, rub a plastic comb on your hair and see if it can pick up tiny scraps of paper.