Answer:
1.57 V
Explanation:
The induced emf ε = -ΔΦ/Δt where Φ = magnetic flux = NABcosθ where N = number of turns of circular coil = 20, A = area of coil = πr² where r = radius of coil = 10.0 cm = 0.1 m , B = strength of magnetic field = 0.30 T,θ = angle between normal to are and magnetic field and Δt = change in time = 0.12 s
Now ΔΦ = change in magnetic flux through circular coil = Φ' - Φ
Φ = magnetic field when A is perpendicular to B , that is θ = 90°. So, Φ = NABcos90 = 0 and Φ' = magnetic field when A is parallel to B , that is θ = 0°. So, Φ' = NABcos0 = NAB
So, ΔФ = Ф' - Ф
= 0 - NAB
= -NAB
= -Nπr²B
= -20 × π(0.1 m)² × 0.30 T
= -0.19 Wb
So, ε = -ΔΦ/Δt
= -(-0.19 Wb)/0.12 s
= 1.57 Wb/s
= 1.57 V
