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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An object is placed 30 cm in front of a concave mirror of focal length 10 cm. The image is formed at:
सही उत्तर: घ) 15 cm in front of the mirror
Using 1/v + 1/u = 1/f with u = −30 cm, f = −10 cm gives v = −15 cm, a real image in front of the mirror. The image lies between F and C because the object is beyond C.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The critical angle for a medium of refractive index √2 (with respect to air) is:
सही उत्तर: ग) 45°
sin C = 1/n = 1/√2, so C = 45°. Total internal reflection occurs for angles of incidence greater than this, going from denser to rarer medium.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The speed of light in a glass is 2 × 10⁸ m/s. The refractive index of the glass is (c = 3 × 10⁸ m/s):
सही उत्तर: ख) 1.5
n = c/v = 3 × 10⁸/(2 × 10⁸) = 1.5. 0.67 is v/c, which is inverted.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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When a source of sound moves towards a stationary listener, the apparent frequency heard is:
सही उत्तर: क) Higher than the actual frequency
Waves get compressed ahead of an approaching source, so the observed frequency increases (Doppler effect). It decreases when the source moves away.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Two tuning forks of frequencies 256 Hz and 260 Hz are sounded together. The number of beats heard per second is:
सही उत्तर: घ) 4
Beat frequency = |f₁ − f₂| = 260 − 256 = 4 Hz. 516 is the sum, which does not give beats.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The fundamental frequency of a pipe closed at one end, of length 0.5 m, is (speed of sound = 340 m/s):
सही उत्तर: ग) 170 Hz
For a closed pipe f = v/4L = 340/2 = 170 Hz. 340 Hz would be the fundamental of an open pipe of the same length (v/2L).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The speed of sound in an ideal gas does NOT depend on:
सही उत्तर: ख) Pressure (at constant temperature)
v = √(γP/ρ) = √(γRT/M); at constant temperature P/ρ stays constant, so changing pressure does not change v. Speed does depend on temperature (v ∝ √T), molar mass and γ.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Sound waves in air are:
सही उत्तर: क) Longitudinal mechanical waves
Sound travels in air as compressions and rarefactions, with particles vibrating along the direction of propagation. Being mechanical, it cannot travel through vacuum.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The ratio of the rms speeds of hydrogen (H₂) and oxygen (O₂) molecules at the same temperature is:
सही उत्तर: घ) 4 : 1
v_rms = √(3RT/M) ∝ 1/√M, so v(H₂)/v(O₂) = √(32/2) = 4. 16:1 is the ratio of the molar masses, not of the speeds.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The ratio of specific heats γ = Cp/Cv for a monatomic ideal gas is:
सही उत्तर: ग) 5/3
For a monatomic gas Cv = 3R/2 and Cp = 5R/2, giving γ = 5/3 ≈ 1.67. 7/5 applies to diatomic gases.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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