इन्जिनियरिङ प्रवेश – Mathematics, Physics, Chemistry, English
इन्जिनियरिङ प्रवेश – Mathematics, Physics, Chemistry, English
Engineering Entrance – Mathematics, Physics, Chemistry & English · ३,८४१ प्रश्न
३,८४१ प्रश्न उपलब्ध। मोड छान्नुहोस्:
इन्जिनियरिङ प्रवेश: 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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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)
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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)
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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)
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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)
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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)
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A soap film (surface tension 0.03 N/m) on a wire frame is enlarged from 10 cm × 6 cm to 10 cm × 10 cm. The work done is:
सही उत्तर: क) 2.4 × 10⁻⁴ J
A film has two surfaces, so W = 2TΔA = 2 × 0.03 × (0.010 − 0.006) = 2.4 × 10⁻⁴ J.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Water (density 1000 kg/m³, viscosity 10⁻³ Pa s) flows at 0.1 m/s through a pipe of diameter 2 cm. The Reynolds number of the flow is:
सही उत्तर: घ) 2000
Re = ρvD/η = 1000 × 0.1 × 0.02/10⁻³ = 2000.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Eight identical rain drops, each falling with terminal velocity v, merge into one drop. The terminal velocity of the big drop is:
सही उत्तर: क) 4v
The radius doubles (volume ×8), and terminal velocity ∝ r², so it becomes 4v.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Water fills a tall tank to height H. A small hole is made in its side at depth h below the surface. The jet strikes the ground farthest from the tank when:
सही उत्तर: ग) h = H/2
Range = v × t = √(2gh) × √(2(H − h)/g) = 2√(h(H − h)), which is greatest when h = H/2.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A pressure of 76 cm of mercury is equal to about:
सही उत्तर: घ) 1.013 × 10⁵ Pa
P = hρg = 0.76 × 13600 × 9.8 ≈ 1.013 × 10⁵ Pa (one standard atmosphere).
💬 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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