Question

A coil of effective area 4 m² is placed at right angles to the magnetic induction B. The e.m.f. of 0.32 V is induced in the coil. When the field is reduced to 20% of its initial value in 0.5 sec. Find B (in wb/m²).

विकल्प

• 0.01

• 0.02

• 0.03

• 0.05

Answer 1

0.05

Explanation:

Given: A = 4 m², e = 0.32 V, dt = 0.5 sec.

B₁ is the initial magnetic induction and when it is reduced to 20% B₂ = 0.2 B₁.

`e = (dphi)/(dt) = (A(B_1 - B_2))/(Deltat)` or 0.32 = `(4(B_1 - 0.2B_1))/0.5`

Magnetic induction `B_1 = 0.16/3.2 = 0.05` Wb/m²