Power in AC Circuits

Practice Questions:

Question 1: easy

In an LR-circuit, the inductive reactance is equal to the resistance R of the circuit. An emf E = E0 cos (wt) applied to the circuit. The power consumed in the circuit is :

1. \[\frac{E_{0}^{2}}{R}\]

2. \[\frac{E_{0}^{2}}{2R}\]

3. \[\frac{E_{0}^{2}}{4R}\]

4. \[\frac{E_{0}^{2}}{8R}\]

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Question 2: easy

A coil has power factor of 0.707 at 60 Hz. Then its power factor at 180 Hz will be :-

1. \[\frac{1}{\sqrt{2}}\]

2. \[\frac{1}{\sqrt{5}}\]

3. \[\frac{1}{\sqrt{10}}\]

4. \[\sqrt{\frac{5}{2}}\]

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