Question

The magnetic flux through a coil of wire containing two loops changes from -65 Wb to +47 Wb in 0.38 s What is the emf induced in the coil? Express your answer using two significant figures

Answer 1

Hi there!

Recall Faraday's Law:

`\epsilon = N(d\Phi_B)/(dt)`

ε = Induced emf (V)

N = Number of Loops

φ = Magnetic Flux (Wb)
t = time (s)

Thus, the induced emf is equivalent to the number of loops of the coil times the rate of change of the magnetic flux bounded by the area of the coil, so:

`\epsilon = 2 \cdot (47 - (-65))/(0.38) = 2 \cdot (112)/(0.38) = 589.47V =\boxed{ 5.9 * 10^2 V}}`

**This is the magnitude of the induced emf. With Lenz's Law, however, the answer would be negative, which just indicates it is a resistive emf.