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 semicircular wire of radius r carrying current I lies in a plane perpendicular to a uniform magnetic field B. The net magnetic force on it is:
सही उत्तर: ख) 2BIr
The force on a curved wire in a uniform field equals that on the straight line joining its ends, of length 2r: F = BI(2r).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Two identical conducting spheres carry charges +3 μC and −1 μC. They are touched together and then separated. The charge on each is now:
सही उत्तर: ग) +1 μC
The total charge +2 μC is shared equally between identical spheres: +1 μC each.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A fish 4 m below the calm surface of water (n = 4/3) sees the whole outside world through a circular window on the surface. The radius of this circle is about:
सही उत्तर: ग) 4.5 m
r = h tan C, where sin C = 3/4 so tan C = 3/√7: r = 12/√7 ≈ 4.5 m.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A convex lens of focal length 20 cm forms a virtual image three times the size of the object. The object distance is about:
सही उत्तर: घ) 13.3 cm
With u = −x and v = −3x: 1/v − 1/u = 1/f gives 2/(3x) = 1/20, so x = 40/3 ≈ 13.3 cm.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Water falls from a height of 420 m. If all its potential energy were converted into heat in the water, its temperature would rise by (g = 10 m/s², c = 4200 J kg⁻¹ K⁻¹):
सही उत्तर: क) 1 K
mgh = mcΔT gives ΔT = gh/c = 10 × 420/4200 = 1 K.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Water rises to a height h in a capillary tube on the Earth. In the same tube on the Moon (g one-sixth that on the Earth), it would rise to:
सही उत्तर: ख) 6h
h = 2T cos θ/(rρg) ∝ 1/g, so the height becomes 6h.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The time period of a simple pendulum whose length equals the radius of the Earth (R = 6.4 × 10⁶ m, g = 9.8 m/s²) is about:
सही उत्तर: ख) 1 hour
For a long pendulum T = 2π√(1/(g(1/l + 1/R))); with l = R, T = 2π√(R/2g) ≈ 3590 s ≈ 60 min.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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At what height above the Earth's surface does the acceleration due to gravity become one-ninth of its surface value? (R = radius of the Earth)
सही उत्तर: ग) 2R
g′ = g R²/(R + h)² = g/9 gives R + h = 3R, so h = 2R.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A projectile is launched with speed u at the angle that gives it the maximum horizontal range on level ground. The maximum height it reaches is:
सही उत्तर: घ) u²/(4g)
Maximum range needs θ = 45°, so H = u² sin²45°/(2g) = u²/(4g), one quarter of the range u²/g.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The moment of inertia of a thin hollow sphere of mass M and radius R about a tangent is:
सही उत्तर: क) 5MR²/3
By the parallel axes theorem: I = (2/3)MR² + MR² = (5/3)MR².
💬 टिप्पणी / गल्ती रिपोर्ट (०)
यी अभ्यास प्रश्न हुन्, आधिकारिक प्रश्न होइनन्। पाठ्यक्रम, विज्ञापन र नतिजाका लागि सम्बन्धित निकायको आधिकारिक वेबसाइट हेर्नुहोस्। उत्तरमा गल्ती भेटे प्रश्नमुनिको "टिप्पणी / गल्ती रिपोर्ट" मा लेख्नुहोस्।
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