Q. No.A series LCR circuit of \({R}=5 ~\Omega, ~~{L}=20~ \text{mH}\) and \(C=0.5~ \mu \text{F} \) is connected across an AC supply of \(250~\text{V}\) having a variable frequency. The power dissipated at resonance condition is:
| 1. | \(105\times10^2~\text W \) | 2. | \(115\times10^2~\text W \) |
| 3. | \(125\times10^2~\text W \) | 4. | \(135\times10^2~\text W \) |
Subtopic: Â Power factor |
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An AC voltage \(V\) is applied across an impedance, that gives rise to a current \(I.\) The angle between \(V\) and \(I\) is \(\theta.\) The power loss is:
1. \(VI \cos\theta\)
2. \(VI \sin\theta\)
3. \(VI/ \cos\theta\)
4. \(VI/ \sin\theta\)
1. \(VI \cos\theta\)
2. \(VI \sin\theta\)
3. \(VI/ \cos\theta\)
4. \(VI/ \sin\theta\)
Subtopic: Â Power factor |
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In which of the following circuits, maximum power dissipation is observed?
1. Pure resistive circuit
2. Pure capacitive circuit
3. Pure inductive circuit
4. None of the above
1. Pure resistive circuit
2. Pure capacitive circuit
3. Pure inductive circuit
4. None of the above
Subtopic: Â Power factor |
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In an ac circuit, the instantaneous e.m.f. and current are given by
\(\begin{aligned} & e=100 \sin 30 t \\ & i=20 \sin \left(30 t-\frac{\pi}{4}\right) \end{aligned}\)
In one cycle of ac, the average power consumed by the circuit and the wattless current are, respectively:
1. \(50, 10\)
2. \(\frac{1000}{\sqrt{2}},10\)
3. \(\frac{50}{\sqrt{2}},0\)
4. \(50,0\)
Subtopic: Â Power factor |
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When AC voltage is applied across an inductor with inductance \(L,\) the average power dissipated across the inductor is:
| 1. | non-zero and greater than one |
| 2. | zero |
| 3. | unity |
| 4. | infinite |
Subtopic: Â Power factor |
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The potential differences across the resistance, capacitance, and inductance are \(80~\text{V}\), \(40~\text{V}\) and \(100~\text{V}\) respectively in an \(LCR\) circuit. The power factor of this circuit is:
1. \(0.4\)
2. \(0.5\)
3. \(0.8\)
4. \(1.0\)
Subtopic: Â Power factor |
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NEET - 2016
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The AC voltage applied to the circuit has a peak value of \(200~\text V\) and an angular frequency, \(\omega=300~\text{s}^{-1}.\) The power factor of this circuit equals:
| 1. | \(\dfrac{3}{5}\) | 2. | \(\dfrac{4}{5}\) |
| 3. | \(\dfrac{3}{4}\) | 4. | \(\dfrac{4}{3}\) |
Subtopic: Â Power factor |
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In a series \(LCR\) circuit, the resistance \(R,\) inductance \(L,\) and capacitance \(C\) are \(10~\Omega,\) \(0.1~\text{H},\) and \(2~\text{mF},\) respectively. If the angular frequency of the AC source is \(100~\text{rad/s},\) the power factor of the circuit is:
| 1. | \(\dfrac{1}{\sqrt{5}}\) | 2. | \(\dfrac{2}{\sqrt{5}}\) |
| 3. | \(\dfrac{3}{\sqrt{5}}\) | 4. | \(\dfrac{2}{2\sqrt{5}}\) |
Subtopic: Â Power factor |
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Two coils \(A\) and \(B\) are connected in series across a \(240~\text{V}, ~50~\text{Hz}\) supply. The resistance of \(A\) is \(5~\Omega\) and the inductance of \(B\) is \(0.02~\text{H}\). The power consumed is \(3~\text{kW}\) and the power factor is \(0.75\). The impedance of the circuit is:
1. \(0.144~\Omega\)
2. \(1.44~\Omega\)
3. \(14.4~\Omega\)
4. \(144~\Omega\)
1. \(0.144~\Omega\)
2. \(1.44~\Omega\)
3. \(14.4~\Omega\)
4. \(144~\Omega\)
Subtopic: Â Power factor |
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An alternating voltage \(V=V_0\sin(\omega t)\) is applied across a circuit. As a result, a current \(I=I_0\sin\Big(\omega t+\dfrac{\pi}{2}\Big)\) flows in it. The power consumed per cycle is:
| 1. | \(\dfrac{V_0I_0}{2}\) | 2. | \(\dfrac{V_0I_0}{\sqrt2}\) |
| 3. | \(\sqrt2V_0I_0\) | 4. | zero |
Subtopic: Â Power factor |
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