When the current in a coil changes from 5 A to 2 A in 0 .1 s , an average voltage of 50…

When the current in a coil changes from 5 A to 2 A in 0.1 s, an average voltage of 50 V is produced. The self-inductance of the coil is
  1. 1.67 H
  2. 6 H
  3. 3 H
  4. 0.67 H

Solution

Magnetic flux

ϕ=LI ⇒ ∆ϕ∆t=L ∆I∆t

∴ εindaverage= ∆ϕ∆t=L ∆I∆t

⇒ 50=L × 5-20.1

⇒  53=L

⇒   L=1.67 H

Asked in: JEE Main 2015 (10 Apr Online)

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