Question

A coil has an inductance of 5 H and a resistance of 20 Ω. If a DC voltage of 100 V is applied to the coil, find the energy stored in the coil when a steady maximum current has been reached

Answer 1

Answer:62.5 J

Explanation:

Given

Inductance(L)=5 H

resistance(R)$=20 \Omega$

Voltage(V)=100 V

$Current=\frac{100}{20}=5 A$

Current in L-R circuit is given by

$I=I_0\left [ 1-e^{-\frac{Rt}{L}}\right ]$

and Power=i^2R+Li\frac{di}{dt}[/tex]

For Steady state i.e. at$t=\infty$

$I=I_0$

Energy Stored is $E=\frac{Li^2}{2}$

$E=\frac{5\times 5^2}{2}=62.5 J$