JEE MainPhysicsElectromagnetic InductionNumerical+4 / −1
The current in a coil of self inductance 2.0 H is increasing according to I = 2 sin(t2) A. The amount of energy spent during the period when current changes from 0 to 2 A is J.
Numerical answer
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Correct answer: 4
- Given data
- Self inductance:
- Current: A
We need the energy spent during the interval in which current changes from to A.
- Energy stored in an inductor
The magnetic energy stored in an inductor carrying current is
So, the energy spent in increasing current from to is
- Initial and final currents
- Initial current:
- Final current:
Thus,
- Why the given time dependence is not needed
Although current is given as , the energy stored in an ideal inductor depends only on the current value, not on how fast or in what manner it reaches that value.
Hence only the change from A to A matters.
- Final answer
So, the amount of energy spent is .
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