Alternating Current - NEET Physics Questions
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Alternating Current

Practice Questions:
Question 51: easy

Which of the following AC circuit will not dissipate energy? (Symbols have their usual meaning)

1. A series LCR circuit
2. A series LR circuit
3. A series LC circuit
4. A series RC circuit
View Answer

In a purely reactive circuit like a series LC circuit, the average power dissipated is zero because the phase difference between the current and voltage is \( 90^\circ \), making the power factor \( \cos\phi = 0 \).

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Question 52: easy

Consider a series \(LCR\) circuit in which reactance and resistance are \(100\ \Omega\) each. When the circuit is connected to ac source \(220\text{ V}\), \(50\text{ Hz}\), then current drawn from the source is

1. \(2.2\sqrt{2}\text{ A}\)
2. \(1.1\sqrt{2}\text{ A}\)
3. \(3.3\sqrt{2}\text{ A}\)
4. \(2.2\text{ A}\)
View Answer

Here, \(R = 100\ \Omega\) and net reactance \(X = 100\ \Omega\). Total impedance is \(Z = \sqrt{R^2 + X^2} = 100\sqrt{2}\ \Omega\). The current \(I = \frac{V}{Z} = \frac{220}{100\sqrt{2}} = 1.1\sqrt{2}\text{ A}\).

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