Lesson 3 of 6 · Magnetism
Experiment⭐ 30 XP⚡ Spark LabThe Motor Effect
Magnetism.
🎯 Your mission
Run the experiment. Find out what really happens.
⚡ The twist
The opposite of what you expect is often what happens.
Mind = Blown
🎢 You feel weightless on a roller coaster because you and the seat are falling at the same speed.
Make a hypothesis first
Predict: what happens if you double the force?
What You'll Learn
A current-carrying wire in a magnetic field experiences a force perpendicular to both, given by F = BIL. Fleming's left-hand rule gives the direction. Reverse either the current or the field and the force reverses — this is what turns an electric motor.
Key Words
Tap a word to see its definition.
Materials Needed
- strong horseshoe magnet
- stiff bare wire
- low-voltage supply
- switch
- leads
Safety First
- Use short pulses only — a shorted wire heats fast enough to burn.
- Low-voltage supply and an adult present.
Steps
Read the explanation above and note the two key terms before you start.
Suspend a wire between the poles of a strong magnet and pass a brief current. Record which way it kicks, then reverse the current and reverse the magnet, tabulating the direction each time against the left-hand rule.
Record what actually happened, including anything that did not match what you expected.
Write a conclusion that answers the question this lesson opened with, and state your uncertainty.
Check Your Understanding
Question 1
1 of 2The force on a current-carrying wire in a magnetic field acts:
Where you see this in real life
You use this every time you flip a light switch, ride a bike, or kick a ball.
Stretch Challenge
Try this in real life this week.
Time how long a small ball rolls down something, then change the slope and try again.
For the dinner table
“Show me something at home that uses this kind of energy.”
Next Smart Experiment
We'll pick an experiment that matches exactly how you're thinking right now.
Share this experiment
Send it to a parent who's looking for a 10-minute kitchen science win.
Ready?
The Motor Effect
Run the experiment. Find out what really happens.
Full screen — no distractions
Checkout complete lesson on Magnetism for 9th Grade
Get the full Magnetism track as a printable PDF — all lessons, worksheets, and answer keys.