Q. No.A resistance \(R\) draws power \(P\) when connected to an AC source. If an inductance is now placed in series with the resistance, such that the impedance of the circuit becomes \(Z\) the power drawn will be:
\(1 .\) \(P \left(\frac{R}{Z}\right)^{2}\)
\(2 .\) \(P \sqrt{\frac{R}{Z}}\)
\(3 .\) \(P \left(\frac{R}{Z}\right)\)
\(4 .\) \(P\)
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| I. | Readings in \(A\) and \(V_2\) are always in phase |
| II. | Reading in \(V_1\) is ahead in phase with reading in \(V_2\) |
| III. | Readings in \(A\) and \(V_1\) are always in phase |
| 1. | I only | 2. | II only |
| 3. | I and II only | 4. | II and III only |
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A coil has resistance and inductive reactance at 50 Hz frequency. If an AC source of 200 V, 100 Hz, is connected across the coil, the current in the coil will be:
1.
2.
3.
4.
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The resistance of a coil for d.c. is in ohms. In a.c., the impedance:
1. Will remain the same
2. Will increase
3. Will decrease
4. Will be zero
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A resistance of 20 ohms is connected to a source of an alternating potential V = 220 sin(). The time taken by the current to change from its peak value to r.m.s value is :
1. 0.2 sec
2. 0.25 sec
3.
4.
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The power factor of a good choke coil is:
(1) Nearly zero
(2) Exactly zero
(3) Nearly one
(4) Exactly one
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The figure shows the variation of \(R\), \(X_L\), and \(X_C\) with frequency \(f\) in a series of \(L\), \(C\), and \(R\) circuits. For which frequency point is the circuit inductive?
| 1. | \(A\) | 2. | \(B\) |
| 3. | \(C\) | 4. | All points |
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In the circuit shown in the figure, the ac source gives a voltage Neglecting source resistance, the voltmeter and ammeter reading will be:
(1) 0V, 0.47A
(2) 1.68V, 0.47A
(3) 0V, 1.4 A
(4) 5.6V, 1.4 A
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In the adjoining figure, the impedance of the circuit will be:
(1) 120 ohm
(2) 50 ohm
(3) 60 ohm
(4) 90 ohm
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(\(f= 50~\text{Hz}\))
| 1. | \(0.052\) H | 2. | \(2.42\) H |
| 3. | \(16.2\) mH | 4. | \(1.62\) mH |
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