भौतिक विज्ञान (Physics) – Physics MCQ
भौतिक विज्ञान (Physics) – CEE प्रवेश
Physics · Medical Entrance (CEE) – Physics, Chemistry, Biology & MAT · ४०७ प्रश्न
४०७ 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 energy of the electron in the second orbit (n = 2) of a hydrogen atom is:
सही उत्तर: ख) −3.4 eV
Eₙ = −13.6/n² eV, so E₂ = −13.6/4 = −3.4 eV. −6.8 eV results from dividing by n instead of n²; −1.51 eV is the n = 3 level.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The energy of a photon of wavelength 620 nm is approximately (take hc = 1240 eV nm):
सही उत्तर: क) 2.0 eV
E = hc/λ = 1240/620 = 2.0 eV. 3.1 eV corresponds to 400 nm (violet light).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In the photoelectric effect, if the intensity of incident light is increased keeping its frequency constant (above threshold), then:
सही उत्तर: घ) The number of photoelectrons emitted increases
Higher intensity means more photons per second, so more electrons are emitted, i.e. a larger photocurrent. The maximum kinetic energy and stopping potential depend only on frequency.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The de Broglie wavelength of a particle of momentum p is:
सही उत्तर: ग) h/p
de Broglie proposed λ = h/p for matter waves. Hence a faster or heavier particle has a shorter wavelength.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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At resonance in a series LCR circuit, the impedance of the circuit is:
सही उत्तर: ख) Equal to R (minimum)
At resonance X_L = X_C, so Z = √(R² + (X_L − X_C)²) = R, its minimum value, and current is maximum. A parallel LC circuit, by contrast, has maximum impedance at resonance.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a purely inductive AC circuit, the current:
सही उत्तर: क) Lags the voltage by 90°
The back emf of the inductor delays the current by a quarter cycle (π/2). In a purely capacitive circuit the current leads the voltage by 90°.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The rms value of the domestic AC supply is 220 V. Its peak value is approximately:
सही उत्तर: घ) 311 V
V₀ = √2 × V_rms = 1.414 × 220 ≈ 311 V. 156 V results from dividing by √2 instead of multiplying.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A transformer has 100 turns in the primary and 500 turns in the secondary. If 220 V AC is applied to the primary, the secondary voltage is:
सही उत्तर: ग) 1100 V
For an ideal transformer Vs/Vp = Ns/Np, so Vs = 220 × 5 = 1100 V. 44 V would be obtained if the turns ratio were inverted, as in a step-down transformer.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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According to Faraday's law of electromagnetic induction, the induced emf in a circuit equals:
सही उत्तर: ख) The rate of change of magnetic flux linked with it
ε = −dφ/dt: a steady flux, however large, induces no emf. The negative sign expresses Lenz's law.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Lenz's law is a consequence of the law of conservation of:
सही उत्तर: क) Energy
The induced current opposes the change producing it, so work must be done to sustain it; otherwise energy would be created. Kirchhoff's junction law, by contrast, comes from charge conservation.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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