भौतिक विज्ञान (Physics) – Physics MCQ
भौतिक विज्ञान (Physics) – CEE प्रवेश
Physics · Medical Entrance (CEE) – Physics, Chemistry, Biology & MAT · ४०७ प्रश्न
४०७ 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 wave is described by y = 0.1 sin(4πt − 0.02πx), where x and y are in cm and t is in s. The speed of the wave is:
सही उत्तर: क) 2 m/s
v = ω/k = 4π/(0.02π) = 200 cm/s = 2 m/s.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A Carnot engine has an efficiency of 25% when its sink is at 27 °C. The temperature of its source is:
सही उत्तर: ग) 127 °C
η = 1 − T₂/T₁ gives 0.25 = 1 − 300/T₁, so T₁ = 400 K = 127 °C.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A cyclist takes a turn of radius 20 m at 10 m/s. The angle with the vertical at which he must lean inward is (g = 10 m/s²):
सही उत्तर: ख) about 27°
tanθ = v²/(rg) = 100/(20 × 10) = 0.5, so θ = tan⁻¹(0.5) ≈ 26.6°, about 27°.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A monatomic ideal gas (γ = 5/3) at 27 °C is compressed adiabatically to 8/27 of its original volume. Its final temperature is:
सही उत्तर: घ) 675 K
TV^(γ−1) = constant: T₂ = 300 × (27/8)^(2/3) = 300 × 9/4 = 675 K.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The wavelength at which a black body radiates most strongly shifts from 500 nm to 250 nm. The total power radiated by it becomes:
सही उत्तर: घ) 16 times
By Wien's law λₘT = constant, so T doubles; by Stefan's law P ∝ T⁴, so power becomes 2⁴ = 16 times.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Two rods of the same material have lengths in the ratio 1 : 2 and radii in the ratio 2 : 1. With the same temperature difference across their ends, the ratio of the rates of heat flow through them is:
सही उत्तर: ग) 8 : 1
Q/t = KAΔT/L ∝ r²/L, so the ratio = (2²/1) : (1²/2) = 4 : 1/2 = 8 : 1.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The heat required to raise the temperature of 0.5 kg of copper (specific heat 400 J kg⁻¹ K⁻¹) from 25 °C to 75 °C is:
सही उत्तर: क) 10 kJ
Q = mcΔT = 0.5 × 400 × 50 = 10000 J = 10 kJ.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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When two blocks of ice are pressed firmly together and the pressure is then released, they join into one block. This phenomenon is called:
सही उत्तर: ख) regelation
Pressure lowers the melting point of ice, so ice at the contact melts; when the pressure is removed the water refreezes and joins the blocks (regelation).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A faulty thermometer reads 5° at the ice point and 95° at the steam point. When it reads 59°, the true temperature is:
सही उत्तर: घ) 60 °C
True T = (reading − 5)/(95 − 5) × 100 = 54/90 × 100 = 60 °C.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A clinical thermometer has a narrow constriction (kink) in its capillary just above the bulb. Its purpose is to:
सही उत्तर: क) prevent the mercury thread from falling back on its own so the reading is retained
The kink breaks the mercury thread when the thermometer is removed from the body, so the maximum reading stays until the thermometer is shaken.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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