An inductor of inducance 5.0 H, having a negligible resistance, is connected in series with a `100 Omega` resistor and a battery of emf 2.0 V. Find the potential difference across the resistor 20 ms after the circuit is switched on.

Explanation

Here ` L= 5.0H, `
` R = 100 Omega , emf = 2.0V `
` t = 20ms = 20 xx (10^-3)s `
` = 2 xx (10^-2) s `
` i_0 = 2/100 `
` tau = L/R = 5/100`
Now ` i= i_0 (1-e^(-t/tau)) `
` I = 2/100 ( 1- e^(( -2 xx (10^-2) xx 100)/5) `
` I = 2/100 (1- e^(-2/5)) `
` = 2/100 (-0.670) `
` = 0.00659 = 0.0066 `
` V = iR = 0.0066 xx 100`
` = 0.66 V `.