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 thin convex glass lens (n = 1.5) is immersed in a transparent liquid of refractive index 1.5. The lens:
सही उत्तर: ग) behaves like a plane glass plate (infinite focal length)
By the lens-maker's formula 1/f ∝ (n_lens/n_medium − 1) = 0, so f is infinite and the lens becomes invisible.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The brilliant sparkling of a cut diamond is mainly due to:
सही उत्तर: घ) total internal reflection
Diamond's high refractive index (about 2.42) gives a small critical angle (about 24°), so light undergoes repeated total internal reflection.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Two musical instruments playing the same note at the same loudness can be distinguished by their:
सही उत्तर: क) quality (timbre)
Quality depends on the number and relative intensities of overtones present along with the fundamental.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A stationary wave differs from a progressive wave in that it:
सही उत्तर: ख) does not transport energy along the medium
In a standing wave energy is trapped between nodes; there is no net flow of energy.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A sound has intensity 10⁻⁸ W/m². Taking the threshold intensity as 10⁻¹² W/m², its intensity level is:
सही उत्तर: ख) 40 dB
β = 10 log₁₀(I/I₀) = 10 log₁₀(10⁴) = 40 dB.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Transverse mechanical waves can travel:
सही उत्तर: ग) in solids and along the surface of liquids, but not through gases
Transverse waves need a restoring force against shear; gases have none, while solids and liquid surfaces (via surface tension and gravity) can support them.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A source of sound moves directly away from a stationary observer at a speed equal to the speed of sound. The apparent frequency is:
सही उत्तर: घ) half the actual frequency
f′ = f v/(v + v_s) = f v/(2v) = f/2.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A burn from steam at 100 °C is more severe than one from water at 100 °C because steam:
सही उत्तर: क) gives out its latent heat of vaporisation on condensing
Each gram of condensing steam releases about 540 cal of latent heat before it starts cooling as water.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A Carnot cycle consists of:
सही उत्तर: क) two isothermal and two adiabatic processes
The Carnot cycle: isothermal expansion, adiabatic expansion, isothermal compression, adiabatic compression.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The Clausius statement of the second law of thermodynamics states that:
सही उत्तर: ख) heat cannot by itself flow from a colder body to a hotter body
Clausius: no process is possible whose sole result is the transfer of heat from a colder to a hotter body.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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