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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In Fleming's left-hand rule for motors, the forefinger (first finger) points in the direction of the:
सही उत्तर: ग) magnetic field
First finger = Field, seCond finger = Current, thuMb = Motion (force).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The SI unit of magnetic permeability is the:
सही उत्तर: ख) henry per metre (H/m)
μ = B/H has units (Wb/m²)/(A/m) = Wb/(A·m) = H/m.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The SI unit of permittivity is the:
सही उत्तर: घ) farad per metre (F/m)
From C = εA/d, ε = Cd/A, so its unit is F·m/m² = F/m.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A lamp connected in series with a suitable capacitor lights up on an AC supply but not on a DC supply of the same voltage because:
सही उत्तर: ख) the capacitor passes alternating current through repeated charging and discharging but blocks steady DC
On AC the capacitor charges and discharges every half-cycle, so current flows in the circuit; with DC it charges once and the current then stops (X_C is infinite at f = 0).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Mica and ceramic (NP0/C0G) capacitors are preferred in high-frequency tuned circuits mainly because they have:
सही उत्तर: क) low dielectric loss and stable capacitance
These dielectrics have very small loss tangent and capacitance that changes little with temperature, which suits RF circuits.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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On a capacitor marked '104J', the letter J indicates a tolerance of:
सही उत्तर: ग) ±5%
In the capacitor letter code F = ±1%, G = ±2%, J = ±5%, K = ±10% and M = ±20%.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A capacitor connected directly across a 230 V (RMS) AC supply must have a voltage rating of at least about:
सही उत्तर: ग) 325 V
The capacitor must withstand the peak voltage, √2 × 230 ≈ 325 V (in practice a higher rating is chosen for safety).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Two capacitors give 9 μF when connected in parallel and 2 μF when connected in series. Their capacitances are:
सही उत्तर: क) 3 μF and 6 μF
C₁ + C₂ = 9 and C₁C₂/(C₁ + C₂) = 2 give C₁C₂ = 18; the numbers with sum 9 and product 18 are 3 and 6 μF.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A 10 μF capacitor is charged from a 100 V DC supply through a 10 kΩ resistor. The charging current one time constant after switching on is about:
सही उत्तर: घ) 3.7 mA
i = (V/R)e^(−t/RC); initial current 100/10 000 = 10 mA, and at t = RC, i = 10 × e⁻¹ ≈ 3.68 mA.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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An air capacitor is charged and then disconnected from the supply. If the plate separation is doubled, the energy stored:
सही उत्तर: ख) doubles
Charge Q stays constant and C halves, so W = Q²/(2C) doubles (the extra energy comes from the work done pulling the plates apart).
💬 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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