A 12 V battery connected to a coil of resistance 6 Ω through a switch, drives a constant current in the circuit. The switch is opened in 1 ms . The emf induced across the coil is 20 V . The inductance of the coil is :

Step-by-step solution

The current i through the circuit is given by i = V R =   12   V 6   Ω =   2   A The formula to calculate the induced emf in the coil can be written as ε = L d i d t       . . . 1 Substitute the values of the known parameters into equation (1) and solve to calculate the inductance of the coil. 20   V = L × 2   A 1 × 10 - 3   s ⇒ L =   20   V × 1 × 10 - 3   s 2   A =   10   mH