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 .

2.15 mV

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 = 0.50 T

Final magnetic field = 0 T

time taken dt = 1.9 s

Area pf the coil = π = 3.142 x = 7.1 x 10^-4 m^2

magnetic flux = BA

initial flux = A = 0.5 x 7.1 x 10^-4 = 3.55 x 10^-4 Wb

Final flux = 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

the independent variable, or the one that is intentionally manipulated is the speed.