Question

A search coil having 2000 turns with area 1.5 cm² is placed in a magnetic field of 0.60T. The coil is moved rapidly out of the field in a time of 0.2 second. Calculate the induced emf across the search coil.

Answer 1

Data: N = 2000, A_i = 1.5 × 10^-4 m², A_f = 0,
B = 0.6T, ∆t = 0.2s
Initial flux, NΦ_f = NBA_i = 2000(0.6)(1.5 × 10^-4)
= 0.18 Wb
Final flux, NΦ_f = 0, since the coil is withdrawn out of the field.
Induced emf,e = $-N\frac{\mathrm{\Delta }{\mathrm{\Phi }}_{\mathrm{m}}}{\mathrm{\Delta }t}=-N\frac{{\mathrm{\Phi }}_{\mathrm{f}}-{\mathrm{\Phi }}_1}{\mathrm{\Delta }t}$
∴ e = $-\frac{0-0.18}{0.2}$ = 0.9V