Question

Find the magnitude of the average induced emf in the coil when the magnet is turned off and the field decreases to 0 T in 2.8 s .

Answer 1

2.15 mV

Step-by-step explanation:

The complete question is

You have a coil of wire with 17 turns each of 1.5 cm radius. You place the plane of the coil perpendicular to a 0.50-TB? field produced by the poles of an electromagnet.

Find the magnitude of the average induced emf in the coil when the magnet is turned off and the field decreases to 0 T in 1.9 s .

Radius of the coil = 1.5 cm = 0.015 m

number of turns = 17

Initial magnetic field
`B_(1)` = 0.50 T

Final magnetic field
`B_(2)` = 0 T

time taken dt = 1.9 s

Area pf the coil = π
`r^(2)` = 3.142 x
`0.015^(2)` = 7.1 x 10^-4 m^2

magnetic flux = BA

initial flux =
`B_(1)`A = 0.5 x 7.1 x 10^-4 = 3.55 x 10^-4 Wb

Final flux =
`B_(2)`A = 0 x 7.1 x 10^-4 = 0 Wb

change in flux dФ = 3.55 x 10^-4 - 0 = 3.55 x 10^-4 Wb

Induced EMF E = NdФ/dt = (17 x 3.55 x 10^-4)/2.8 = 2.15 x 10^-3 V

==> 2.15 mV