1) For a current-carrying inductor, emf associated is 20m V. Now, the current through it changes from 6A to 2A in 2 s. The coefficient of mutual inductance is A) 20mH B) 10mH C) 1mH D) 2mH Answer: Option BExplanation:|e|=LdIdt Here, e= 20mV= 20x 10-3 V dIdt=6−22=2A/s L= ? ⇒20×10−3=L×2 ∴ L= 10x 10-3= 10mH