भौतिक विज्ञान (Physics) – Physics MCQ
भौतिक विज्ञान (Physics) – इन्जिनियरिङ प्रवेश
Physics · Engineering Entrance – Mathematics, Physics, Chemistry & English · १,३९८ प्रश्न
१,३९८ प्रश्न उपलब्ध। मोड छान्नुहोस्:
भौतिक विज्ञान (Physics): 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 a vacuum flask (thermos), the silvering of the inner walls mainly reduces heat transfer by:
सही उत्तर: ग) radiation
Silvered surfaces are poor emitters and good reflectors of radiation; the vacuum stops conduction and convection.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The coefficient of volume expansion of an ideal gas at constant pressure and absolute temperature T is:
सही उत्तर: घ) 1/T
V = nRT/P, so (1/V)(dV/dT) = 1/T.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The molar specific heat of an ideal gas in an isothermal process is:
सही उत्तर: घ) infinite
Heat is added but ΔT = 0, so C = Q/(nΔT) is infinite.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The surface tension of a liquid is numerically equal to its:
सही उत्तर: क) surface energy per unit area
The work done to increase the surface area by unit amount (isothermally) equals the surface tension.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The upward lift on an aeroplane wing is mainly explained by:
सही उत्तर: ख) Bernoulli's principle
Air flows faster over the curved upper surface, so pressure there is lower than below (Bernoulli), producing lift.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A material that breaks soon after its elastic limit is crossed is called:
सही उत्तर: ग) brittle
Brittle materials (e.g. glass, cast iron) fracture with little plastic deformation beyond the elastic limit.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Two perpendicular SHMs x = A sin ωt and y = A sin 2ωt are superposed. The resulting Lissajous figure is:
सही उत्तर: ग) a figure of eight
A frequency ratio of 1 : 2 with these phases gives the figure-of-eight shaped Lissajous curve y = 2x√(1 − x²/A²).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A particle in SHM has a maximum speed of 10 m/s and a maximum acceleration of 50 m/s². Its amplitude is:
सही उत्तर: घ) 2 m
v_max = Aω and a_max = Aω², so ω = 50/10 = 5 rad/s and A = 10/5 = 2 m.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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For a particle in SHM with total energy E, the average kinetic energy over one complete cycle is:
सही उत्तर: क) E/2
KE = E cos²(ωt + φ), whose average over a cycle is E/2 (the average PE is also E/2).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A mass hangs from a spring and oscillates vertically. Compared with the same mass and spring oscillating horizontally on a smooth table, its period is:
सही उत्तर: ख) the same
Gravity only shifts the equilibrium position; the period T = 2π√(m/k) is unchanged.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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