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# Force, current and Electric Field: How a motor rotates

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1. Hi, a teacher gave me a question from a edexcel past paper A2 unit 4 and i am having troubles understanding how force, current and field works on one question:

http://www.edexcel.com/migrationdocu...e_20110127.pdf

Question 13, A and B

I don't understand mark scheme, so could any prove help. I'll appreciate it!
2. Bump
3. If you could show us the mark scheme and state what it is you don't understand it would help us to answer your question.
4. (Original post by Stonebridge)
If you could show us the mark scheme and state what it is you don't understand it would help us to answer your question.
Q13 a and b:http://www.edexcel.com/migrationdocu...s_20110309.pdf
5. It might help if you indicate which part of the mark scheme you have a problem with.

In any case, without seeing the mark scheme, this is how I'd answer the question;

The coil turns due to the motor effect; since current is flowing through the coil and the coil is placed in a magnetic field, then there is a force acting on the coil. Using Fleming's left hand rule, we can say that the length of coil DC will have a vertical force acting up, and the length of coil BA will have a vertical force acting down, hence rotating the coil anti-clockwise. I would then draw arrows on the diagram indicating the direction and location of those forces.
6. (Original post by Rysm)
It might help if you indicate which part of the mark scheme you have a problem with.

In any case, without seeing the mark scheme, this is how I'd answer the question;

The coil turns due to the motor effect; since current is flowing through the coil and the coil is placed in a magnetic field, then there is a force acting on the coil. Using Fleming's left hand rule, we can say that the length of coil DC will have a vertical force acting up, and the length of coil BA will have a vertical force acting down, hence rotating the coil anti-clockwise. I would then draw arrows on the diagram indicating the direction and location of those forces.
Very much appreciated. I have a better understanding thanks.

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