Question

60. A coil has an inductance of 53 mH and a resistance of 0.35 ohm.
If a 12V emf is applied across the coil, how much energy is stored in the magnetic field after the current has built up to its equilibrium value ?
(A) 23 J
(B) 31 J
(C) 55 J
(D) 100 J

Answer 1

Answer:

(B) 31 J

Explanation:

Given that

Inductance = 53 mH

Resistance = 0.35 ohm.

Emf = 12 V

We know that energy stored in coil given as

$E=\dfrac{1}{2}L I^2$

We also know that

V = I.R

12 = 0.35 I

I= 34.28 A

Now by putting the values

$E=\dfrac{1}{2}L I^2$

$E=\dfrac{1}{2}\times 53\times 10^{-3}\times 34.28^2\ J$

E = 31.14 J

So the our option B is correct.

(B) 31 J