आधारभूत विद्युत् (Basic Electrical) – Basic Electrical Engineering MCQ
आधारभूत विद्युत् (Basic Electrical) – इलेक्ट्रिकल र टेलिकम
Basic Electrical Engineering · Technical – Electrical, Mechanical & Telecom · २,२९९ प्रश्न
२,२९९ प्रश्न उपलब्ध। मोड छान्नुहोस्:
आधारभूत विद्युत् (Basic Electrical): प्रश्न र उत्तर
सही लागेको विकल्पमा थिच्नुहोस्। सही भए हरियो, गलत भए रातो देखिन्छ; ३ सेकेन्डपछि सही उत्तर र व्याख्या देखिन्छ।
सही: ० / ०
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In complex form, the apparent power S of an AC load is written as:
सही उत्तर: क) P + jQ
Complex power S = P + jQ, whose magnitude is the apparent power in VA.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a single-phase AC circuit, the instantaneous power pulsates at a frequency of:
सही उत्तर: ख) twice the supply frequency
p = v x i contains a term cos(2wt), so instantaneous power varies at twice the supply frequency.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A coil has an inductive reactance of 100 ohm and a resistance of 5 ohm at a certain frequency. Its quality factor Q at that frequency is:
सही उत्तर: घ) 20
Q of a coil = X_L / R = 100 / 5 = 20.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Because of their behaviour at resonance, series and parallel resonant circuits are respectively called:
सही उत्तर: ख) acceptor and rejector circuits
A series resonant circuit offers minimum impedance (accepts) at resonance, while a parallel one offers maximum impedance (rejects).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A practical parallel resonant circuit has a coil of inductance L and resistance R in parallel with a capacitor C. Its dynamic impedance at resonance is:
सही उत्तर: ग) L / (CR)
At resonance the circuit behaves as a pure resistance of value L / (CR), which is high when R is small.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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At resonance, the current drawn from the supply by a parallel (tank) resonant circuit is:
सही उत्तर: क) minimum
A parallel resonant circuit has maximum impedance at resonance, so the line current is minimum.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The half-power (cut-off) frequencies of a series resonant circuit are those at which the current falls to:
सही उत्तर: ग) 0.707 times its value at resonance
Power is proportional to I^2, so half power occurs when the current is 1/sqrt 2, about 0.707, of the maximum.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A single-phase load draws 10 A from a 230 V supply at a power factor of 0.8 lagging. Its reactive power is:
सही उत्तर: ग) 1380 VAR
sin phi = sqrt(1 - 0.8^2) = 0.6, so Q = V I sin phi = 230 x 10 x 0.6 = 1380 VAR.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A current of 10 A flows through a series circuit of R = 6 ohm and X_L = 8 ohm. The active power consumed is:
सही उत्तर: क) 600 W
Only the resistance consumes active power: P = I^2 R = 10^2 x 6 = 600 W.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a series RL circuit, the voltage across the resistor is 30 V and across the pure inductor is 40 V. The supply voltage is:
सही उत्तर: घ) 50 V
The two voltages are 90 degrees apart, so V = sqrt(30^2 + 40^2) = 50 V.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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