Question

The component of the external magnetic field along the central axis of a 125-turn circular coil of radius 34.0 cm decreases from 2.40 T to 0.600 T in 1.60 s. If the resistance of the coil is 1.50 Ω, what is the magnitude of the induced current in the coil?

Answer 1

The induced emf is:

V = n*dφ/dt = n*Δφ/Δt

where "Δφ" is the change in magnetic flux, "Δt" is the change in time, and "n" is the number of turns. However, instead of the flux, we have magnetic flux density (B) given. To find the change in flux, the change in flux density needs to be multiplied by the area.

V = n*A*ΔB/Δt

where "A" is the area of the coil. A is π*r^2 = π*(0.34)^2 =0.36298 m^2

V = 125*(0.36298)*(1.8)/1.6 = 51.044 Volts

The current (assuming the coil is short circuited) is:

I = V / R = 51.044/1.5 = 48.7A = 34.02 A