Question

60. A coil has an inductance of 53 mH and a resistance of 0.35S2. 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:

The current flowing through the coil  i = Voltage÷Resistance

Voltage=12V Resistance= 0.35

Current i = 12÷ 0.35= 34.28

Energy stored in inductor = L×i²÷ 2

                                      =  53×10^-3 × 34.38²÷ 2

                                     =31J

The energy stored is 31J              

Answer 2

Given that,

Inductance of the coil is 53 mH

Resistance of the coil is 0.35 ohms

Emf of the coil is 12 V

To find,

The energy is stored in the magnetic field after the current has built up to its equilibrium value.

Solution,

The energy stored in the magnetic field is given by :

$E=\dfrac{1}{2}LI^2$

I is electric current

Ohm's law,

$V=IR\\\\I=\dfrac{V}{R}\\\\I=\dfrac{12}{0.35}\\\\I=34.28\ A$

So,

$E=\dfrac{1}{2}\times 53\times 10^{-3}\times 34.28^2\\E=31.14\ J$

So, the correct option is (B) "31 J".

Learn more,

Energy stored in magnetic field

https://brainly.in/question/12601301