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Induced emf in loop

The current in the long straight wire AB of the figure is upward and is increasing steadily at a rate of di/dt.

1. what is the total flux in through the loop?

2. what is the induced emf in the loop?


Solution Preview

To calculate the flux, you first need to know the magnetic field at a distance r from the wire. This is given by:

B(r,t) = mu_{0} I(t)/(2 pi r)

The direction of the magnetic field is according to the right hand rule; if your thumb points in the direction of the current then your fingers point in the way the magnetic field points to. So for positive I, B points into the paper where you've drawn the loop.

The flux is given by the integral of B(r,t) over the surface of the loop. You need to define the sign of the flux by choosing a direction for the outward ...

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