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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If the current through a resistor is doubled, the heat produced in the same time becomes:
सही उत्तर: ग) Four times
Joule's law: H = I²Rt, so H ∝ I² and doubling I gives 4H.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A Wheatstone bridge with arms P, Q, R and S is balanced when:
सही उत्तर: ख) P/Q = R/S
At balance no current flows through the galvanometer, giving P/Q = R/S. The metre bridge is based on this condition.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A cell of emf 2 V and internal resistance 0.5 Ω is connected to an external resistance of 3.5 Ω. The current in the circuit is:
सही उत्तर: क) 0.5 A
I = E/(R + r) = 2/(3.5 + 0.5) = 0.5 A. 0.57 A results from ignoring the internal resistance.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Kirchhoff's junction (current) law is based on conservation of:
सही उत्तर: घ) Charge
The sum of currents entering a junction equals the sum leaving, because charge cannot accumulate at the junction. The loop (voltage) law is based on energy conservation.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A wire of resistance R is stretched uniformly to double its length (volume constant). Its new resistance is:
सही उत्तर: ग) 4R
Doubling length halves the area, so R = ρL/A becomes ρ(2L)/(A/2) = 4R. 2R ignores the reduction in area.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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An electric dipole placed in a uniform electric field experiences:
सही उत्तर: ख) Zero net force but possibly a torque
The forces qE and −qE on the two charges are equal and opposite, so net force is zero, but they can form a couple with torque τ = pE sinθ.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The electric potential at a distance of 9 cm from a point charge of 1 μC is (1/4πε₀ = 9 × 10⁹ N m² C⁻²):
सही उत्तर: क) 1 × 10⁵ V
V = kq/r = 9 × 10⁹ × 10⁻⁶ / 0.09 = 10⁵ V. Remember V ∝ 1/r, whereas the field E ∝ 1/r².
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The energy stored in a 10 μF capacitor charged to 100 V is:
सही उत्तर: ग) 0.05 J
U = ½CV² = ½ × 10 × 10⁻⁶ × 100² = 0.05 J. 0.1 J results from omitting the factor ½.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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When a dielectric slab of dielectric constant K completely fills the space between the plates of a parallel-plate capacitor, its capacitance:
सही उत्तर: ख) Becomes K times
C = Kε₀A/d, so capacitance increases K times. For an isolated charged capacitor, the potential difference then decreases by K.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The electric field inside a charged hollow conducting sphere is:
सही उत्तर: क) Zero
All charge resides on the outer surface, and by Gauss's law the enclosed charge is zero, so E = 0 inside. The potential inside, however, is constant and non-zero.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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