Use the expression for the magnetic field of a loop to find an expression for the magnitude of the magnetic field at point P, a distance a/2 from the center of each coil Note that there is a total of 2N turns in the two coils.

Explanation:

The magnitude of the magnetic field at a point P, a distance a/2 from the center of the each coil can be determined as follows;

Let the magnitude be M;

Note that there is a total of 2N turns in the two coils.

So, we have:

where x = distance (d) which is given as a/2; we have:

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when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.