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 glass slab 12 cm thick (n = 1.5) is placed over a mark on paper. Viewed from above, the mark appears raised by:
सही उत्तर: ख) 4 cm
Normal shift = t(1 − 1/n) = 12(1 − 2/3) = 4 cm.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In the displacement method, the screen is 100 cm from the object and the two lens positions giving sharp images are 20 cm apart. The focal length of the lens is:
सही उत्तर: क) 24 cm
f = (D² − d²)/(4D) = (10000 − 400)/400 = 24 cm.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A convex lens forms a real image twice the size of the object on a screen 90 cm from the object. The focal length of the lens is:
सही उत्तर: ख) 20 cm
u + v = 90 with v = 2u gives u = 30 cm and v = 60 cm; 1/f = 1/30 + 1/60 = 1/20, so f = 20 cm.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A biconvex lens (n = 1.5) has radii of curvature 10 cm and 15 cm. Its focal length in air is:
सही उत्तर: ग) 12 cm
1/f = (n − 1)(1/R₁ − 1/R₂) = 0.5(1/10 + 1/15) = 0.5 × 1/6 = 1/12, so f = 12 cm.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A concave mirror of focal length 20 cm forms a real image 60 cm in front of it. The object distance is:
सही उत्तर: घ) 30 cm
1/u = 1/f − 1/v = 1/20 − 1/60 = 2/60, so u = 30 cm (in front of the mirror).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A pipe closed at one end has the same fundamental frequency as a pipe of length 60 cm open at both ends. The length of the closed pipe is:
सही उत्तर: ख) 30 cm
v/(4L_c) = v/(2 × 60) gives L_c = 30 cm.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A wave is described by y = 0.1 sin(10πt − πx/5) in SI units. Its wavelength is:
सही उत्तर: घ) 10 m
k = π/5 rad/m, so λ = 2π/k = 10 m.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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For the resonance-tube readings l₁ = 16 cm and l₂ = 50 cm (first and second resonances), the end correction is:
सही उत्तर: क) 1 cm
e = (l₂ − 3l₁)/2 = (50 − 48)/2 = 1 cm.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a resonance-tube experiment with a 512 Hz fork, the first and second resonances occur at air-column lengths of 16 cm and 50 cm. The speed of sound is about:
सही उत्तर: ग) 348 m/s
l₂ − l₁ = λ/2 = 0.34 m, so λ = 0.68 m and v = fλ = 512 × 0.68 ≈ 348 m/s.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A 0.5 m string of mass 5 g is stretched between two fixed points with a tension of 100 N. Its fundamental frequency is:
सही उत्तर: घ) 100 Hz
μ = 0.005/0.5 = 0.01 kg/m, v = √(T/μ) = 100 m/s, f = v/(2L) = 100 Hz.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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