A magnet pushed at 0.5 m/s into a coil of 100 turns induces 0.8 V.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A magnet pushed at into a coil of turns induces . The voltage grows in step with the speed and with the number of turns. Find the voltage when
- the magnet moves at ,
- the coil has turns and the magnet moves at ,
- both changes are made together.
Need a reminder? The key ideaShow
A current is induced in a coil while the magnetic field through it changes: when a magnet and the coil move relative to each other. It is larger for faster motion, a stronger magnet and more turns; it reverses when the motion reverses, and it opposes the change (Lenz's law). Fleming's right-hand rule: thumb for the motion, forefinger for the field, middle finger for the induced current.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) .
Step 2. (b) .
Step 3. (c) .
Answer: , and .
Check. A stronger magnet would also raise the voltage; a magnet at rest gives .
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