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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The electric field at a distance r from an infinitely long straight wire with uniform linear charge density λ is:
सही उत्तर: क) λ/(2πε₀r)
Applying Gauss's law to a coaxial cylinder of length l: E·2πrl = λl/ε₀, so E = λ/(2πε₀r).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The force between two point charges of 1 μC each placed 1 m apart in vacuum is (1/(4πε₀) = 9 × 10⁹ N m² C⁻²):
सही उत्तर: घ) 9 × 10⁻³ N
F = 9 × 10⁹ × (10⁻⁶)²/1² = 9 × 10⁻³ N.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The dispersive power ω of the material of a thin prism is given by:
सही उत्तर: ग) (n_v − n_r)/(n − 1)
ω = angular dispersion/mean deviation = (n_v − n_r)/(n − 1), where n is the mean refractive index.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The magnifying power of a compound microscope can be increased by:
सही उत्तर: ख) decreasing the focal lengths of the objective and the eyepiece
M ≈ (L/f₀)(D/fₑ), so smaller focal lengths of the objective and the eyepiece give greater magnification.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In Young's double-slit experiment, if the separation between the slits is doubled (other things unchanged), the fringe width becomes:
सही उत्तर: क) half
Fringe width β = λD/d, so doubling d halves β.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Myopia (short-sightedness) is corrected by using:
सही उत्तर: घ) a concave lens
In myopia the image of distant objects forms in front of the retina; a diverging (concave) lens shifts it back onto the retina.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A ray of light passes from air into glass of refractive index √3 with an angle of incidence of 60°. The angle of refraction is:
सही उत्तर: ग) 30°
sin r = sin 60°/√3 = (√3/2)/√3 = 1/2, so r = 30°.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Lenses of power +2 D and −0.5 D are placed in contact. The focal length of the combination is about:
सही उत्तर: ख) 66.7 cm
P = 2 − 0.5 = +1.5 D, so f = 1/1.5 m ≈ 0.667 m = 66.7 cm (converging).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The image of a real object formed by a convex mirror is always:
सही उत्तर: क) virtual, erect and diminished
A convex mirror diverges light, so for any real object the image is virtual, erect, diminished and lies between the pole and focus.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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An object is placed 15 cm in front of a concave mirror of focal length 10 cm. The image is formed:
सही उत्तर: घ) 30 cm in front of the mirror
With u = −15 cm and f = −10 cm, 1/v = 1/f − 1/u = −1/10 + 1/15 = −1/30, so v = −30 cm: a real image 30 cm in front.
💬 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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