Question 226: Electromagnetic Induction

Question

The coefficient of mutual induction is 2 H and induced e.m.f. across secondary is 2 kV . Current in the primary is reduced from 6 A to 3 A . The time required for the change of current is

Accepted Answer

Given:
Coefficient of mutual induction, $M = 2~	ext{H}$
Induced emf, $E = 2~	ext{kV} = 2000~	ext{V}$
Change in current in primary, $\Delta I = 6~	ext{A} - 3~	ext{A} = 3~	ext{A}$ (it is reduced, so $\Delta I = -3~	ext{A}$ but magnitude is enough)
Required: Time taken, $\Delta t$
According to NCERT, the induced emf due to mutual induction is:
$$ E = M \frac{\Delta I}{\Delta t} $$
Rearrange to solve for $\Delta t$:
$$ \Delta t = M \frac{\Delta I}{E} $$
Substitute the values:
$$ \Delta t = \frac{2 	imes 3}{2000} $$
Calculate:
$$ \Delta t = \frac{6}{2000} = 0.003~	ext{s} $$
or
$$ \Delta t = 3 	imes 10^{-3}~	ext{s} $$
Correct option: Option D ($3 	imes 10^{-3}~\mathrm{s}$)

Answer

$4 	imes 10^{-3} \mathrm{~s}$

Answer

$6 	imes 10^{-3} \mathrm{~s}$

Answer

$2 	imes 10^{-3} \mathrm{~s}$

Answer

$3 	imes 10^{-3} \mathrm{~s}$

Electromagnetic Induction

The coefficient of mutual induction is 2 H and induced e.m.f. across secondary is 2 kV . Current in the primary is reduced from 6 A to 3 A . The time required for the change of current is

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