Question

A coil having a resistance of 20 ohm and inductance 20 H is connected to 120 V battery. Find the value of energy stored in the magnetic field when the steady state is reached?

• A. 250J
• B. 150J
• C. 300J
• D. 360J

Answer 1

The correct option is D

360J

$R=20\Omega ,V=120v,L=204$

$E=\frac{1}{2}{\left(\frac{V}{R}\right)}^2=\frac{1}{2}\times 20\times {\left(\frac{120}{20}\right)}^2=360J$