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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The efficiency of a Carnot engine would be 100% only if:
सही उत्तर: घ) the sink were at absolute zero
η = 1 − T₂/T₁ equals 1 only when T₂ = 0 K, which is unattainable.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A gas absorbs 100 J of heat and does 40 J of work on its surroundings. The change in its internal energy is:
सही उत्तर: घ) 60 J
ΔU = Q − W = 100 − 40 = 60 J.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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For one mole of an ideal gas, the molar specific heats are related by (Mayer's relation):
सही उत्तर: ख) Cp − Cv = R
Mayer's relation: Cp − Cv = R.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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For an ideal gas taken through a complete cyclic process, the change in its internal energy is:
सही उत्तर: ग) zero
Internal energy is a state function; the system returns to its initial state, so ΔU = 0.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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1 kg of ice at 0 °C is mixed with 1 kg of water at 80 °C. Taking the latent heat of fusion of ice as 80 cal/g, the final temperature of the mixture is:
सही उत्तर: क) 0 °C
Heat given by water cooling to 0 °C = 1000 × 1 × 80 = 80 000 cal, exactly enough to melt 1000 g of ice; so all ends as water at 0 °C.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The value of the Stefan–Boltzmann constant σ is about:
सही उत्तर: ख) 5.67 × 10⁻⁸ W m⁻² K⁻⁴
σ ≈ 5.67 × 10⁻⁸ W m⁻² K⁻⁴ (1.38 × 10⁻²³ J K⁻¹ is Boltzmann's constant and 2.9 × 10⁻³ m K is Wien's constant).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a satellite orbiting the Earth, water in a capillary tube dipped in it will:
सही उत्तर: घ) rise to the full length of the tube
h = 2T cos θ/(rρg); in the weightless condition effective g = 0, so the water rises up to the top of the tube whatever its length.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The pressure due to water alone at a depth of 10 m in a lake is (ρ = 1000 kg/m³, g = 10 m/s²):
सही उत्तर: क) 1 × 10⁵ Pa
P = hρg = 10 × 1000 × 10 = 10⁵ Pa.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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According to Stokes' law, the viscous drag on a small sphere of radius r moving with speed v through a fluid of viscosity η is:
सही उत्तर: ग) 6πηrv
Stokes' law: F = 6πηrv.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a hydraulic press, the pistons have areas 10 cm² and 100 cm². A force of 50 N on the smaller piston can support a load of:
सही उत्तर: क) 500 N
Equal pressure: F₂ = F₁ × A₂/A₁ = 50 × 10 = 500 N.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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