Try it on paper first. A hint, the key idea and the worked solution are here when you need them.
A circular loop has a radius of cm. It is in a uniform field of T. Find the flux through the loop in three positions. First the normal to the loop is along the field. Then the normal makes an angle of with the field. Last, the loop is turned through a half turn, to .
The flux through a flat loop is , with the angle between the field and the normal to the loop. A coil of turns has the flux linkage . Faraday's law gives . The current is , and the charge that flows is .
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. cm m, T.
Step 1. The area. .
Step 2. The three fluxes.
Answer: mWb, mWb and mWb.
Check. A half turn changes the flux from to , a change of mWb. This is why a flipped coil gives twice the emf of a coil that is turned through a quarter turn.
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