Give two ways to make a simple motor turn the other way.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
- Give two ways to make a simple motor turn the other way.
- A motor's largest turning effect is . The current is raised from to , and a magnet times as strong is fitted. What is the largest turning effect now?
Need a reminder? The key ideaShow
In a motor, the two sides of a coil feel opposite forces, so the coil turns. The split ring (commutator) reverses the current every half turn, so it keeps turning one way. The largest turning effect is ; at an angle between the coil's plane and the field it is .
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) Reverse the current (turn the battery round), or reverse the field (turn the magnet round). Doing both leaves the direction as it was.
Step 2. (b) The current is times as large, and the field times as strong: .
Answer: (a) reverse the current, or reverse the field. (b) .
Check. More turns or a larger coil would also make it stronger.
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