Question

The current in coil changes from 0.6 A to 3 A in 0.06 s inducing a voltage of 8 V across it. Find initial energy stored in the coil.

Options

• 7.2 J

• 6.2 J

• 12.5 J

• 22.5 J

Answer 1

7.2 J

Explanation:

`"emf" = "L" = "di"/"dt"`

` = (3 - 0.6)/0.06 = 40`

`"E"_"stored"= 1/2  "Li"^2`

` = 1/2 xx 40 xx 0.6^2`

` = 7.2  "J"`