In a coil, the current changes from -2 ~A to +2 ~A in 0.2 ~s and induces an emf of 0.1 ~V . The self inductance of the coil is :

Correct answer: C. 5 mH (E m f)_ induced =-L (d i)/(d t) In magnitude form, aligned & |Emf_ ind |=|(-) L di dt | & 0.1= (L)[+2-(-2)] 0.2 & L=(0.1 × 0.2)/(4)=5 mH aligned

JEE Main 20246 AprilEvening Shift

Exam: JEE Main
Year: 2024
Date: 6 April
Shift: Evening Shift
Subject: Physics
Chapter: Electromagnetic Induction

JEE Main 2024 · 6 April · Evening Shift · Physics · Electromagnetic Induction

In a coil, the current changes from -2 ~A to +2 ~A in 0.2 ~s and...

In a coil, the current changes from

-2 \mathrm{~A}

+2 \mathrm{~A}

0.2 \mathrm{~s}

and induces an emf of

0.1 \mathrm{~V}

. The self inductance of the coil is :

Options

A $4 \mathrm{mH}$
B $1 \mathrm{mH}$
C $5 \mathrm{mH}$
D $2.5 \mathrm{mH}$

Correct answer

C. $5 \mathrm{mH}$

Step-by-step solution

(E m f)_{\text{induced }}=-L \frac{d i}{d t}

In magnitude form,

\begin{aligned} & \left|\operatorname{Emf}_{\text{ind }}\right|=\left|(-) L \frac{\mathrm{di}}{\mathrm{dt}}\right| \\ & \Rightarrow 0.1=\frac{(\mathrm{L})[+2-(-2)]}{0.2} \\ & \Rightarrow \mathrm{L}=\frac{0.1 \times 0.2}{4}=5 \mathrm{mH} \end{aligned}

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