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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A temperature of 300 K corresponds to:
सही उत्तर: घ) 27 °C
T(°C) = T(K) − 273 = 300 − 273 = 27 °C. 573 results from adding 273 instead of subtracting.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Surface tension of a liquid generally ______ with increase in temperature.
सही उत्तर: ग) Decreases
Higher temperature weakens intermolecular cohesive forces, so surface tension decreases and becomes zero at the critical temperature. That is why hot water cleans better.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The gauge pressure (excess over atmospheric) at a depth of 10 m in water is (ρ = 1000 kg/m³, g = 10 m/s²):
सही उत्तर: ख) 1 × 10⁵ Pa
P = ρgh = 1000 × 10 × 10 = 1 × 10⁵ Pa, roughly equal to one atmosphere. So every 10 m of water adds about 1 atm of pressure.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Water flows through a pipe whose cross-section reduces from 4 cm² to 1 cm². If the speed in the wider part is 2 m/s, the speed in the narrower part is:
सही उत्तर: क) 8 m/s
Equation of continuity: A₁v₁ = A₂v₂, so v₂ = 4 × 2 / 1 = 8 m/s. 0.5 m/s results from inverting the area ratio.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Bernoulli's theorem for fluid flow is based on conservation of:
सही उत्तर: घ) Energy
Bernoulli's equation P + ½ρv² + ρgh = constant expresses energy conservation per unit volume. The equation of continuity expresses conservation of mass.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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If the radius of a capillary tube is halved, the height to which water rises in it becomes:
सही उत्तर: ग) Double
By Jurin's law h = 2T cosθ/(rρg), so h ∝ 1/r. Halving r doubles the height.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The excess pressure inside a soap bubble of radius r and surface tension T is:
सही उत्तर: ख) 4T/r
A soap bubble has two free surfaces, so excess pressure = 2 × 2T/r = 4T/r. For a liquid drop (single surface) it is 2T/r.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Hooke's law (stress ∝ strain) holds strictly up to the:
सही उत्तर: क) Proportional limit
Stress is proportional to strain only up to the proportional limit; beyond it the graph is no longer linear. Beyond the yield point the material deforms plastically.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The value of the universal gravitational constant G is approximately:
सही उत्तर: ग) 6.67 × 10⁻¹¹ N m² kg⁻²
G ≈ 6.67 × 10⁻¹¹ N m² kg⁻², and it is the same everywhere. 9.8 m/s² is the acceleration due to gravity g, which varies with place.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The weight of a body at the centre of the Earth is:
सही उत्तर: ख) Zero
At the centre, g = g(1 − R/R) = 0, so weight mg = 0. The mass of the body, however, remains unchanged.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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