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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For light of a given frequency above the threshold, increasing the intensity of the light incident on a photosensitive surface:
सही उत्तर: ख) increases the photoelectric current
Higher intensity means more photons per second and so more photoelectrons, but their maximum KE depends only on frequency.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The photoelectric effect provides evidence for the:
सही उत्तर: घ) particle (photon) nature of light
Instantaneous emission and the threshold frequency are explained only by light consisting of photons of energy hf.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A choke coil is preferred to a resistor for controlling current in an AC circuit because:
सही उत्तर: क) it consumes almost no power
An ideal inductor has power factor nearly zero, so it limits current without dissipating energy as heat.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A capacitor blocks steady direct current because its reactance for DC (f = 0) is:
सही उत्तर: ग) infinite
X_C = 1/(2πfC) → ∞ as f → 0.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a series LCR circuit at resonance, the power factor is:
सही उत्तर: क) 1
At resonance X_L = X_C, so Z = R and cos φ = R/Z = 1.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The cores of transformers are laminated in order to reduce:
सही उत्तर: ग) eddy current losses
Thin insulated laminations increase resistance to eddy currents and so reduce the associated losses.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The magnetic flux through a coil changes uniformly from 0.5 Wb to 0.1 Wb in 0.2 s. The magnitude of the induced emf is:
सही उत्तर: घ) 2 V
|e| = ΔΦ/Δt = 0.4/0.2 = 2 V.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a moving-coil galvanometer, the magnets are given concave pole pieces and a soft-iron core is used so that:
सही उत्तर: ख) the field is radial and the deflection is proportional to the current
In a radial field the plane of the coil is always parallel to the field, so the torque NIAB is independent of deflection and θ ∝ I.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Above its Curie temperature, a ferromagnetic substance becomes:
सही उत्तर: ग) paramagnetic
Thermal agitation destroys domain alignment above the Curie temperature, so the material behaves paramagnetically.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A charged particle enters a uniform magnetic field with its velocity inclined at an angle (other than 0° or 90°) to the field. Its path is a:
सही उत्तर: ख) helix
The parallel component is unchanged while the perpendicular component produces circular motion, giving a helix.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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