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JEE Mains · Physics · STD 12 -Electromagnetic induction
  • JEE Mains 2022
  • Medium
  • Numerical

The current in a coil of self inductance \(2.0 \,H\) is increasing according to \(I =2 \sin \left( t ^{2}\right) A\). The amount of energy spent during the period when current changes from \(0\) to \(2\, A\) is......\(J.\)

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Answer & Solution

Correct Answer

(A) \(4\)

Step-by-step Solution

Detailed explanation

\(I =2 \sin \left( t ^{2}\right) \Rightarrow dI =4 t \sin \left( t ^{2}\right) dt\)

If \(I =0 \Rightarrow t =0\)

and \(I=2 \Rightarrow 2=2 \sin t^{2}\)

\(\Rightarrow t =\sqrt{\frac{\pi}{2}}\)

\(E =\int LI dI\)

\(=\int 2 \times 2 \sin \left( t ^{2}\right) \times 4 t \cos \left( t ^{2}\right) dt\)

\(=8 \int_{0}^{\sqrt{\pi / 2}} t \sin \left(2 t^{2}\right) d t\)

\(=2\left[-\cos \left(2 t^{2}\right)\right]_{0}^{\sqrt{\pi / 2}}\)

\(=2[-\cos \pi+\cos 0]=4\)

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