Question 182: Electromagnetic Induction

Question

A 10 $$\Omega$$, 20 mH coil carrying constant current is connected to a battery of 20 V through a switch. Now after switch is opened current becomes zero in 100 $$\mu$$s. The average e.m.f. induced in the coil is ____________ V.

Accepted Answer

Initially current, $${I_0} = {{20} \over {10}} = 2A$$ (when initially switch closed)
average emf induced in coil $$ = {{Ldi} \over {dt}}$$
$$ \Rightarrow {e_{avg}} = {{20 	imes {{10}^{ - 3}} 	imes (2 - 0)} \over {100 	imes {{10}^{ - 6}}}}$$
$${e_{avg}} = 400\,V$$

Electromagnetic Induction

A 10 $\Omega, 20 mH coil carrying constant current is connected to a battery of 20 V through a switch. Now after switch is opened current becomes zero in 100 \mu$s. The average e.m.f. induced in the coil is ____________ V.

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