Question

A flat coil with 78 loops of wire has a radius of 15 mm. The coil is placed in a magnetic field of 0.35 T so that a maximum flux goes through it. It is later rotated in 0.07 s to a position so that no flux can go through. What is the average induced EMF produced between the terminals of the coil?

Answer 1

Magnetic field

$A=\pi r^2$

$A=\pi \times0.015^2$

$e=N\frac{d\phi}{dt}$

$\phi=BAcos\theta$

$\phi_{max}=BA$

Cos0°=1

$$e=78\times\frac{0.35\times\pi \times0.015^2}{0.07-0}=0.275V$$