Question

The self induced emf of a coil is 25 volts. When the current in it is changed at uniform rate from 10 A to 25 A is 1 s, the change in the energy of the inductance is :

• A. 437.5 J
• B. 637.5 J
• C. 740 J
• D. 540 J

Answer 1

Answer: (A)

437.5 J

$L\frac{di}{dt}=25$
$L\times \frac{15}{1}=25$
$L=\frac{5}{3}H$
$\Delta E=\frac{1}{2}\times \frac{5}{3}({25}^2-{10}^2)=\frac{5}{6}\times 525=437.5J$