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 coaxial cable has insulation of relative permittivity 4, and the ratio of outer to inner radius equals e (≈ 2.718). Its capacitance per metre is about (ε₀ = 8.85 × 10⁻¹² F/m):
सही उत्तर: ख) 222 pF/m
C per metre = 2πε₀ε_r/ln(b/a) = 2π × 8.85 × 10⁻¹² × 4/1 ≈ 2.22 × 10⁻¹⁰ F/m = 222 pF/m.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Just after a DC source is switched onto an uncharged series RC circuit, the voltage across the resistor is:
सही उत्तर: ख) equal to the supply voltage
An uncharged capacitor's voltage cannot change instantly, so at t = 0⁺ it acts as a short circuit and the whole supply voltage appears across R.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A DC voltage is switched onto a series RL circuit. One time constant later, the energy stored in the inductor is about what percentage of its final value?
सही उत्तर: क) 40%
i = 0.632 I_final, and energy ∝ i², so W = 0.632² ≈ 0.40 of the final energy.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A series RLC circuit is switched onto a DC source. Its current oscillates with decaying amplitude (underdamped) when:
सही उत्तर: ग) R < 2√(L/C)
The characteristic roots are complex when (R/2L)² < 1/(LC), i.e. R < 2√(L/C).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A series RLC circuit has L = 1 H and C = 1 μF. Its transient response is critically damped when R equals:
सही उत्तर: ख) 2000 Ω
Critical damping requires R = 2√(L/C) = 2√(10⁶) = 2000 Ω.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A capacitor already charged to 5 V is connected through a resistor to a 10 V DC source. After a time τ ln 2 (τ = RC), its voltage is:
सही उत्तर: क) 7.5 V
v(t) = 10 − (10 − 5)e^(−t/τ); with e^(−ln 2) = 1/2, v = 10 − 2.5 = 7.5 V.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A discharged 100 Ah battery is charged at 10 A. If its ampere-hour efficiency is 80%, the charging time needed is about:
सही उत्तर: क) 12.5 h
Ah to be supplied = 100/0.8 = 125 Ah, so time = 125/10 = 12.5 h.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A solar panel of area 1.6 m² delivers 320 W under an irradiance of 1000 W/m². Its conversion efficiency is:
सही उत्तर: ग) 20%
Efficiency = 320/(1.6 × 1000) = 0.20 = 20%.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A 60 W incandescent lamp used 5 hours a day is replaced by a 9 W LED lamp of similar light output. The energy saved in 30 days is:
सही उत्तर: घ) 7.65 kWh
Saving = (60 − 9) W × 5 h × 30 = 7650 Wh = 7.65 kWh.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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One metric horsepower is equal to about:
सही उत्तर: घ) 735.5 W
Metric hp = 75 kgf·m/s = 75 × 9.80665 ≈ 735.5 W; the British hp is 746 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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