HC Verma: Concepts of Physics - Volume 2 Alternating Current Pages 329-330: Q4 Solution: An inductor coil of some resistance is connected to an AC…

QPages 329-330: Q4: HC Verma: Concepts of Physics - Volume 2 Alternating Current Pages 329-330: Q4 Solution: An inductor coil of some resistance is connected to an AC…

⚠️ Common Exam Traps & Conceptual Pitfalls

Students often confuse the average of a sinusoidal quantity with the average of its square or absolute value. The instantaneous current $i(t)=I_0sinomega t$ and induced emf $e(t)=-L,di/dt$ are sinusoidal and integrate to zero over a full period, so their mean values vanish. However, the instantaneous power dissipated in the resistor is $p(t)=i^2(t)R$, and the magnetic energy stored is $u(t)= frac12L,i^2(t)$; both involve $i^2(t)$, which is always positive, so their averages over a cycle are positive, not zero. Always check whether the quantity is linear in the sinusoid or involves its square before deciding its mean value.

An inductor coil of some resistance is connected to an AC source. Which of the following quantities have zero average value over a cycle?

Multiple Choice Options

A Current
B Induced emf in the inductor
C Joule heat
D Magnetic energy stored in the inductor

Step-by-Step Verified Solution

**Answer:** (a), (b). **Step-by-Step Explanation:** Current and induced emf have zero average over a cycle. Joule heat and magnetic energy are always positive.

QPages 329-330: Q4: HC Verma: Concepts of Physics - Volume 2 Alternating Current Pages 329-330: Q4 Solution: An inductor coil of some resistance is connected to an AC…

Multiple Choice Options

Step-by-Step Verified Solution

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