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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Standard resistors and ammeter shunts are made of alloys such as manganin or constantan mainly because these alloys have:
सही उत्तर: घ) A very low temperature coefficient of resistance
Their resistance hardly changes with temperature, so the resistor value stays accurate as it warms up.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The temperature coefficient of resistance of annealed copper at 20 °C is about:
सही उत्तर: ख) 0.00393 per °C
Copper's resistance rises by about 0.393% per °C near room temperature (about 0.00427 per °C referred to 0 °C).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A conductor has 10^28 free electrons per m^3 and a cross-section of 1 mm^2. If the drift velocity is 1 mm/s, the current is (e = 1.6 x 10^-19 C):
सही उत्तर: ग) 1.6 A
I = n A v e = 10^28 x 10^-6 x 10^-3 x 1.6 x 10^-19 = 1.6 A.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The drift velocity of free electrons in a copper wire carrying an ordinary current is typically:
सही उत्तर: क) A fraction of a millimetre to a few millimetres per second
Electrons drift very slowly (around mm/s); the electric signal travels fast because the field is set up almost instantly along the whole wire.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In electrolysis, a current of 5 A is passed for 1000 s through a solution of a metal with electrochemical equivalent 3.3 x 10^-7 kg/C. The mass of metal deposited is:
सही उत्तर: क) 1.65 g
m = z I t = 3.3 x 10^-7 x 5 x 1000 = 1.65 x 10^-3 kg = 1.65 g.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a fluorescent tube light circuit, the choke (ballast):
सही उत्तर: घ) produces a high voltage surge to strike the tube and then limits its current
When the starter opens, the choke's induced emf ignites the tube, and afterwards its reactance limits the tube current.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A lamp of 100 candela is mounted 2 m from a point on a surface, and the light reaches the surface at 60 degrees to the normal. Using Lambert's cosine law, the illuminance at that point is:
सही उत्तर: क) 12.5 lux
E = I cos(theta) / d^2 = 100 x 0.5 / 2^2 = 12.5 lux.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The electrolyte used in a nickel-iron (Edison) alkaline cell is:
सही उत्तर: ख) potassium hydroxide solution
Nickel-iron and nickel-cadmium cells are alkaline cells using a potassium hydroxide (KOH) electrolyte.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The specific gravity of the electrolyte in a lead-acid battery is measured with a:
सही उत्तर: ख) hydrometer
A hydrometer floats in the electrolyte drawn into it and indicates its specific gravity, showing the state of charge.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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When a lead-acid cell discharges:
सही उत्तर: क) the positive and negative plates change towards lead sulphate and the electrolyte's specific gravity falls
During discharge PbO2 and Pb both form PbSO4, and water is produced, diluting the acid.
💬 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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