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
-
A single machine produces a sound level of 60 dB at a point. Two identical machines running together produce a level of about:
सही उत्तर: ख) 63 dB
Intensity doubles, so the level rises by 10 log₁₀2 ≈ 3 dB, giving about 63 dB.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
A sonometer wire is stretched by a solid weight of relative density 8. When the weight is fully immersed in water, the fundamental frequency changes from f to about:
सही उत्तर: क) 0.94 f
Buoyancy reduces the tension to (7/8) of its value; since f ∝ √T, f′ = f√(7/8) ≈ 0.94 f.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
A car approaches a large wall at 10 m/s sounding a 500 Hz horn. The frequency of the echo heard by the driver is about (speed of sound 340 m/s):
सही उत्तर: घ) 530 Hz
The wall receives f₁ = 500 × 340/330 and reflects it; the moving driver hears f₁ × 350/340 = 500 × 350/330 ≈ 530 Hz.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
A stationary wave is y = 0.1 sin(πx/3) cos(40πt) in SI units. The distance between two adjacent nodes is:
सही उत्तर: ग) 3 m
k = π/3 gives λ = 2π/k = 6 m, and adjacent nodes are λ/2 = 3 m apart.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
In the van der Waals equation (P + a/V²)(V − b) = RT for one mole, the constant b accounts for:
सही उत्तर: क) the finite volume of the gas molecules
b is the excluded volume due to the molecules' own size; a corrects for intermolecular attraction.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
Two rods of equal length and equal cross-section, of conductivities K₁ and K₂, are placed side by side (in parallel) between the same two reservoirs. Their equivalent conductivity is:
सही उत्तर: ख) (K₁ + K₂)/2
In parallel the heat currents add: K_eq(2A) = K₁A + K₂A, so K_eq = (K₁ + K₂)/2.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
An ideal (Carnot) heat pump keeps a room at 27 °C while the outside is at −3 °C. Its coefficient of performance is:
सही उत्तर: ग) 10
COP of a heat pump = T_h/(T_h − T_c) = 300/(300 − 270) = 10.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
A black sphere's radius is doubled and its absolute temperature is halved. The total power it radiates becomes:
सही उत्तर: ग) one-fourth
P ∝ r²T⁴, so the factor is 2² × (1/2)⁴ = 4/16 = 1/4.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
When a liquid is heated in a glass vessel, its real coefficient of expansion γ_r, apparent coefficient γ_a and the vessel's coefficient γ_g are related by:
सही उत्तर: क) γ_r = γ_a + γ_g
The observed (apparent) expansion is the real expansion of the liquid minus the expansion of the vessel, so γ_r = γ_a + γ_g.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
Water rises to a vertical height h in a capillary tube. If the tube is tilted to make 60° with the vertical, the length of the water column in it becomes:
सही उत्तर: ग) 2h
The vertical height remains h, so the length along the tube is h/cos 60° = 2h.
💬 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।
नमस्ते! पाठ्यक्रम, सामान्य ज्ञान, भाषा परीक्षा वा कुनै प्रश्नको उत्तर बुझ्न सोध्नुहोस्।
AI ले गल्ती गर्न सक्छ। महत्वपूर्ण कुरा आधिकारिक स्रोतमा जाँच्नुहोस्।