Electrical Circuits

251. When the net reactance in a series coil-capacitor circuit is zero at frequency f, the nature of its reactance of frequency 2f is

1. Inductive
2. Capacitive
3. Resistive
4. Infinite

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252. When the power factor of a circuit is zero,

1. Power absorbed is maximum
2. Power absorbed is minimum
3. Power absorbed is zero
4. The impedance is minimum

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253. When the temperature of copper wire is increased its resistance is

1. Increased
2. Decreased
3. Constant
4. Zero

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254. When two coils of identical reactance are in parallel without mutual inductance, the reactance of the combination is __________ the reactance of each coil.

1. One half
2. Twice
3. Four times
4. One fourth

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255. When two complex conjugates are subtracted, the result is a

1. Quadrature component only
2. Complex component
3. In-phase component
4. Real component

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256. When two in-phase sine waves that have identical frequency and amplitude are added together, then the result is a sine wave with __________ the amplitude of either.

1. Half
2. Twice
3. Four times
4. One-fourth

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257. When two pure sine waves of the same frequency and the same amplitude which are exactly 180° out-of-phase are added together, the result is

1. A wave with twice the amplitude
2. A wave with half the amplitude
3. Zero signal
4. A wave with twice the frequency

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258. When two unequal values of resistors are connected in parallel across a dc source, greater current flows through the

1. Higher resistance
2. Lower resistance
3. Higher wattage resistance
4. Lower wattage resistance

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259. When voltage is applied across a ceramic dielectric the electrostatic field produced is 50 times greater than air dielectric. The dielectric constant of ceramic therefore is

1. 50
2. 100
3. 16.67
4. 5

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260. Which component opposes voltage change?

1. Resistor
2. Inductor
3. Capacitor
4. Transistor

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