# An emf is rotating a 1107 turn, 20.0 cm diameter coil in Earth's 2.73*10^-5 T magnetic field. What average emf is induced, given the plane of the coil is originally perpendicular ot the Earth's field and is rotated to be parallel to the field in 10 ms?

Oct 31, 2015

$949 , 4 m V$

#### Explanation:

By Faraday's Law, the emf induced in a coil is directly proportional to the rate of change of magnetic flux through the coil.
$\therefore {\epsilon}_{i} = - N \frac{\mathrm{dp} h {i}_{B}}{\mathrm{dt}} = - N \frac{d}{\mathrm{dt}} \left(B A\right) = - N B \frac{\mathrm{dA}}{\mathrm{dt}}$

$= - \left(1107\right) \left(2 , 73 \times {10}^{- 5}\right) \frac{0 - \left(\pi \times 0 , {10}^{2}\right)}{0 , 001}$

$= 0 , 9494 V$