प्राविधिक – इलेक्ट्रिकल, मेकानिकल र टेलिकम
प्राविधिक – इलेक्ट्रिकल, मेकानिकल र टेलिकम
Technical – Electrical, Mechanical & Telecom · ४,५०० प्रश्न
४,५०० प्रश्न उपलब्ध। मोड छान्नुहोस्:
इलेक्ट्रिकल र टेलिकम: 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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A major advantage of a three-phase supply over a single-phase supply is that:
सही उत्तर: ख) it delivers constant total power and needs less conductor material for the same power
Balanced three-phase systems give constant instantaneous power and economical transmission, and allow self-starting motors.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In the two-wattmeter method, if one wattmeter reads zero, the power factor of the balanced load is:
सही उत्तर: क) 0.5
One reading becomes zero when the phase angle is 60 degrees, and cos 60 degrees = 0.5.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In the two-wattmeter method of measuring three-phase power, if both wattmeters read equal values, the power factor of the load is:
सही उत्तर: ग) unity
Equal readings mean the phase angle is zero, i.e. power factor 1.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a delta-connected three-phase system, the line voltage is:
सही उत्तर: ख) equal to the phase voltage
Each phase winding is connected directly between two lines, so V_L = V_ph in delta.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a balanced three-phase star-connected system, the current in the neutral wire is:
सही उत्तर: ख) zero
The three balanced phase currents are 120 degrees apart and add up to zero.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a series RC circuit, the current:
सही उत्तर: ग) leads the applied voltage by an angle between 0 and 90 degrees
The capacitive reactance makes the current lead, but the resistance keeps the angle below 90 degrees.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A major disadvantage of operating a load at a low power factor is that:
सही उत्तर: क) it draws more current for the same active power, increasing losses
I = P / (V cos phi), so a lower power factor needs more current and causes larger I^2 R losses.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The reciprocal of impedance in an AC circuit is called:
सही उत्तर: क) admittance
Admittance Y = 1/Z, measured in siemens; its imaginary part is susceptance.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A pure inductor of reactance 23 ohm is connected to a 230 V AC supply. The current drawn is:
सही उत्तर: क) 10 A
I = V / X_L = 230 / 23 = 10 A.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Multiplying a phasor by the operator j rotates it by:
सही उत्तर: ग) 90 degrees counter-clockwise
j = 1 at an angle of 90 degrees, so multiplication by j advances the phasor by 90 degrees.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
यी अभ्यास प्रश्न हुन्, आधिकारिक प्रश्न होइनन्। पाठ्यक्रम, विज्ञापन र नतिजाका लागि सम्बन्धित निकायको आधिकारिक वेबसाइट हेर्नुहोस्। उत्तरमा गल्ती भेटे प्रश्नमुनिको "टिप्पणी / गल्ती रिपोर्ट" मा लेख्नुहोस्।
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