InterviewSolution
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InterviewSolution
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Define an inductor. Derive equation of energy U=1/2LI^2 stored in inductor. |
Answer» Solution :In a CIRCUIT, a component which has SELF inductance is called an inductor. Symbol for an inductor in a circuit is the one shown in figure.  This self-induced emf is also called the back emf as it opposes any change in the current in a circuit. So, work needs to be done against the back emf (e) in establishing the current. This work done is stored as magnetic potential energy. For the current I at an instant in a circuit, the rate of work done is, `(dW)/(dt)=|epsilon|I=LI(dI)/(dt)` `therefore` dW=LIdI Total amount of work done in establishing the current I is, `W=int_0^1 dW=int_0^1 LIdI=1/2LI^2` Thus, the electrical energy required to build up the current I is, `U=1/2LI^2` This expression reminds us of `mv^2//2` for the (MECHANICAL) kinetic energy of a particle of mass m, and SHOWS that L is analogous to m (i.e., L is electrical INERTIA and opposes growth and decay of current in the circuit). |
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