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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The illuminance at a workplace is measured with a:
सही उत्तर: क) lux meter
A lux meter uses a photocell calibrated to read illuminance in lux (lm/m²).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A thin mirror strip is provided beside the scale of many analogue meters in order to:
सही उत्तर: घ) avoid parallax error while reading
The reading is taken when the pointer hides its own reflection, so the eye is exactly above the pointer and parallax is avoided.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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For measuring resistances in the medium range (about 1 Ω to 100 kΩ) accurately, the instrument generally used is the:
सही उत्तर: ग) Wheatstone bridge
The Wheatstone bridge suits medium resistances; the Kelvin double bridge is used for very low ones and the megger for insulation (very high) resistance.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In measurement, 'precision' refers to:
सही उत्तर: क) how closely repeated readings agree with one another
Precision is the repeatability or consistency of readings; closeness to the true value is accuracy, and the smallest detectable change is resolution.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a three-phase four-wire system feeding non-linear single-phase loads (such as computers), which harmonic currents add up in the neutral instead of cancelling?
सही उत्तर: घ) the third harmonic and its odd multiples (triplen harmonics)
Triplen harmonics (3rd, 9th, ...) of the three phases are in phase with each other, so they add in the neutral, which can overload it.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a balanced three-phase supply, the phasor sum of the three phase voltages is:
सही उत्तर: ख) zero
Three equal phasors 120° apart form a closed triangle, so their sum is zero at every instant.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a series RLC circuit at resonance, the voltages across the inductor and the capacitor are:
सही उत्तर: ग) equal in magnitude and 180° out of phase
At resonance X_L = X_C, so IX_L = IX_C; V_L leads the current by 90° and V_C lags by 90°, so they cancel.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Expressed in the form Y = G + jB, the admittance of a pure inductor of reactance X_L is:
सही उत्तर: ख) −j/X_L (a negative susceptance)
Y = 1/(jX_L) = −j/X_L, so an inductor has negative (inductive) susceptance, while a capacitor has +jωC.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A 50 Hz sinusoidal voltage starts from zero. The time it takes to reach its positive peak is:
सही उत्तर: घ) 5 ms
The peak occurs a quarter-cycle after the zero crossing: T/4 = (1/50)/4 = 5 ms.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A resistor dissipates an average power of 100 W from a sinusoidal supply. The maximum instantaneous power it takes during a cycle is:
सही उत्तर: क) 200 W
p = VmIm sin²ωt has a maximum VmIm = 2VrmsIrms = 2P_avg = 200 W.
💬 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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