Alice builds an electric motor by positioning an electromagnet between the poles of a permanent magnet. The electromagnet spins as the current running through it repeatedly switches directions.How could Alice decrease the force that the permanent magnet applies on the electromagnet? A. increase the electric current running through the electromagnet B. decrease the number of turns in the electromagnet's coil C. replace the magnet with a stronger magnet D. decrease the distance between the magnet's poles and the electromagnet
Question
Alice builds an electric motor by positioning an electromagnet between the poles of a permanent magnet. The electromagnet spins as the current running through it repeatedly switches directions.How could Alice decrease the force that the permanent magnet applies on the electromagnet? A. increase the electric current running through the electromagnet B. decrease the number of turns in the electromagnet's coil C. replace the magnet with a stronger magnet D. decrease the distance between the magnet's poles and the electromagnet
Solution
Alice could decrease the force that the permanent magnet applies on the electromagnet by decreasing the distance between the magnet's poles and the electromagnet. This is because the force between two magnets is inversely proportional to the square of the distance between them. Therefore, by decreasing the distance, the force would also decrease. This corresponds to option D.
Option A, increasing the electric current, would actually increase the force because it would strengthen the electromagnet. Option B, decreasing the number of turns in the coil, could potentially weaken the electromagnet and thus decrease the force, but it would also likely affect the motor's performance. Option C, replacing the magnet with a stronger one, would increase the force, not decrease it.
Similar Questions
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