One hundred turns of insulated copper wire are wrapped around an iron core of cross-sectional area 0.100m2. As the magnetic field along the coil axis changes from 0.5 T to 1.00T in 4s, the voltage induced is:

The voltage induced in the coil  is 1.25 V.

Explanation:

Given;

number of turns, N = 100 turns

cross sectional area of the copper coil, A = 0.1 m²

initial magnetic field, B₁ = 0.5 T

final magnetic field, B₂ = 1.00 T

duration of change in magnetic field, dt = 4 s

The induced emf in the coil is calculated as;

Therefore, the voltage induced in the coil  is 1.25 V.