Q. No.A transistor-oscillator using a resonant circuit with an inductance \(L\) (of negligible resistance) and a capacitance \(C\) has a frequency \(f\). If \(L\) is doubled and \(C\) is changed to \(4C\), the frequency will be:
1. \(\frac{f}{4}\)
2. \(8f\)
3. \(\frac{f}{2\sqrt{2}}\)
4. \(\frac{f}{2}\)
1. \(\frac{f}{4}\)
2. \(8f\)
3. \(\frac{f}{2\sqrt{2}}\)
4. \(\frac{f}{2}\)
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A transistor is operated in common emitter configuration at constant collector voltage Vc = 1.5 V such that a change in the base current from 100 μA to 150 μA produces a change in the collector current from 5 mA to 10 mA. The current gain (β) is:
1. 67
2. 75
3. 100
4. 50
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The photoelectric effect is used by a photocell to convert:
| 1. | Change in the frequency of light into a change in electric voltage. |
| 2. | Change in the intensity of illumination into a change in photoelectric current. |
| 3. | Change in the intensity of illumination into a change in the work function of the photocathode. |
| 4. | Change in the frequency of light into a change in the electric current. |
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The following figure shows a logic gate circuit with two inputs A and B and the output C. The voltage waveforms of A, B, and C as shown below:
The logic circuit gate is :
1. AND gate
2. NAND gate
3. NOR gate
4. OR gate
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For a p-type semiconductor, which of the following statements is true?
1. Electrons are the majority carriers and pentavalent atoms are the dopants.
2. Electrons are the majority carriers and trivalent atoms are the dopants.
3. Holes are the majority carriers and trivalent atoms are the dopants.
4. Holes are the majority carriers and pentavalent atoms are the dopants.
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The ideal diodes are connected in the two branches as shown in the figure.. Current through the battery is:
1. 2A
2. 1A
3. 3A
4. 4A
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Zener diodes with breakdown voltage ranging over 2 V — 200 V are commercially available. The breakdown voltage of a Zener diode:
1. Increases with increasing doping concentration
2. Decreases with increasing doping concentration
3. Does not depend on doping concentration
4. May increase or decrease with increasing doping concentration
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A Zener diode of breakdown voltage, = 10 V is used in the given circuit. The current through the load resistor is:
1. 10
2. 5
3. 10 mA
4. 5 mA
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The figure shows an n-p-n transistor. Choose the correct statement out of the following.
1. Collector-base junction, as well as emitter-base junction both, are forward biased.
2. Collector-base junction, as well as emitter-base junction both, are reverse biased.
3. Collector-base junction is forward biased and the emitter-base junction is reverse biased.
4. Collector-base junction is reverse-biased and the emitter-base junction is forward biased.
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In the circuit shown in the figure, the current amplification factor () is 80. Neglecting base-
emitter voltage (), calculate the collector current :
1. 0.78 mA
2. 0.96 mA
3. 1.28 mA
4. 2.20 mA
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