Question

In an LR circuit $f=50Hz,L=2H,E=5volts,R=1\Omega$ then energy stored in inductor is

• A. $50J$
• B. $25J$
• C. $100J$
• D. None of these

Answer 1

The correct option is D None of these

$L=2H,E=5volts,R=1\Omega$

Energy in inductor $=\frac{1}{2}L{I}^{2}I=\frac{E}{Z}$

$I=\frac{5}{\sqrt{R^2+{\left(\omega L\right)}^2}}=\frac{5}{\sqrt{1+4{\pi }^2\times {50}^2\times 4}}$

$=\frac{5}{\sqrt{1+{\left(200\pi \right)}^2}}=\frac{5}{200\pi }$

Energy $=\frac{1}{2}\times 2\times \frac{5\times 5}{200\times 200{\pi }^2}=6.33\times {10}^{-5}$