AL physics (motor)

2011-06-25 8:38 pm

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I don't understand the explanation of option 1. As far as I am concerned, initially there is a change of magnetic flux as the coil is continuously rotating (cutting the magnetic flux). When it is suddenly jammed, the magnetic flux changes from certain value to zero. As such, the rate of change of magnetic flux should be very large. But it contradicts to the solution, why???

回答 (1)

Knowledge enhance Life

2011-06-26 5:06 am

✔ 最佳答案

Think clearly,
Magnetic flux = (B-field)x(Area)
Although the coil does not rotate,magnetic field still existed(remains unchanged)

Thus,
－B-field & Area remain unchanged ---> Magnetic flux remains unchanged.
－Magnetic flux passing through the coil remains unchange
( There is no mistake in solution.)
　 which mean there is no change in magnetic flux,
the magnetic flux changes from certain value to zero in a short time,
so emf is very large.

Be careful of the words.

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