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 stationary wave, the distance between a node and the adjacent antinode is:
सही उत्तर: क) λ/4
Consecutive nodes are λ/2 apart, and an antinode lies midway between them, so node-to-antinode distance is λ/4.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The speed of a transverse wave on a string under tension 100 N with linear mass density 0.01 kg/m is:
सही उत्तर: घ) 100 m/s
v = √(T/μ) = √(100/0.01) = √10⁴ = 100 m/s. 10⁴ m/s is T/μ without taking the square root.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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When a sound source moves towards a stationary observer, the frequency heard by the observer:
सही उत्तर: ग) Increases
By the Doppler effect, the waves get compressed in front of an approaching source, so the apparent frequency increases. It decreases when the source moves away.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The fundamental frequency of a pipe of length 0.85 m closed at one end is (speed of sound = 340 m/s):
सही उत्तर: ख) 100 Hz
For a closed pipe f = v/(4L) = 340/(4 × 0.85) = 100 Hz. 200 Hz would be the fundamental if the pipe were open at both ends.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A wave has a frequency of 500 Hz and a wavelength of 0.68 m. Its speed is:
सही उत्तर: क) 340 m/s
v = fλ = 500 × 0.68 = 340 m/s. This is a typical value for the speed of sound in air.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In which medium does sound travel fastest?
सही उत्तर: घ) Steel
Sound speed depends on elasticity and density; solids like steel have very high elasticity, giving about 5000 m/s or more. Sound cannot travel through vacuum at all.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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If the amplitude of a simple harmonic oscillator is doubled, its total energy becomes:
सही उत्तर: ख) Four times
Total energy E = ½kA² ∝ A², so doubling A makes E four times. The time period, however, does not depend on amplitude.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In simple harmonic motion, the acceleration of the particle is maximum at:
सही उत्तर: क) The extreme positions
a = −ω²x, which is maximum in magnitude where |x| is maximum, i.e. at the extremes. At the mean position the velocity, not the acceleration, is maximum.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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According to the second law of thermodynamics, it is impossible to:
सही उत्तर: घ) Convert heat completely into work in a cyclic process
The Kelvin–Planck statement says no cyclic engine can convert all absorbed heat into work. Converting work completely into heat (e.g. friction) is easily possible.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The average translational kinetic energy of a gas molecule at absolute temperature T is:
सही उत्तर: ग) (3/2)kT
From kinetic theory, average translational KE = (3/2)kT, independent of the nature of the gas. (1/2)kT is the energy per degree of freedom.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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