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A lamp is connected in series with a cap...

A lamp is connected in series with a capacitor. Predict your observations for dc and ac connections. What happens in each case if the capacitance of the capacitor is reduced?

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When a dc source is connected to a capacitor, the capacitor gets charged and after charging no current flows in the circuit and the lamp will not glow. There will be no change even if C is reduced. With ac source, the capacitor offers capacitative reactance (`1//omegaC)` and the current flows in the circuit. Consequently, the lamp will shine. Reducing C will increase reactance and the lamp will shine less brightly than before.
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NCERT GUJARATI-ALTERNATING CURRENT-ADDITIONAL EXERCISES
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  2. An LC circuit contains a 20 mH inductor and a 50 muF capacitor with an...

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  3. A coil of inductance 0.50 H and resistance 100Omega is connected to a ...

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  4. If the circuit is connected to a high frequency supply (240 V, 10 kHz)...

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  5. A 100 muF capacitor in series with a 40 Omega resistance is connected ...

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  6. If the circuit is connected to a 110 V, 12 kHz supply? Hence, explain ...

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  7. Keeping the source frequency equal to the resonating frequency of the ...

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  8. A circuit containing a 80 mH inductor and a 60 muF capacitor in series...

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  9. Suppose the circuit in has a resistance of 15 W. Obtain the average p...

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  10. A series LCR circuit with L = 0.12 H, C = 480 nF, R = 23 Omega is conn...

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  11. Obtain the resonant frequency and Q-factor of a series LCR circuit wit...

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  12. In any ac circuit, is the applied instantaneous voltage equal to the a...

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  13. A capacitor is used in the primary circuit of an induction coil.

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  14. An applied voltage signal consists of a superposition of a dc voltage ...

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  15. A choke coil in series with a lamp is connected to a dc line. The lamp...

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  16. Why is choke coil needed in the use of fluorescent tubes with ac mains...

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  17. A power transmission line feeds input power at 2300 V to a stepdown tr...

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  18. At a hydroelectric power plant, the water pressure head is at a height...

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  19. A small town with a demand of 800 kW of electric power at 220 V is sit...

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  20. Do the same exercise as above with the replacement of the earlier tran...

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