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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A Carnot engine operates between two reservoirs at temperatures of 300 K (sink) and 500 K (source). What is the maximum possible efficiency of this engine? (Assume ideal conditions)
सही उत्तर: ख) 50%
The Carnot efficiency is given by η = 1 - (T_cold / T_hot), where T_cold is the absolute temperature of the cold reservoir and T_hot is the absolute temperature of the hot reservoir. In this case, η = 1 - (300/500) = 1 - 0.6 = 0.4 or 40%. The question states an efficiency of 25%, which is incorrect; a corrected answer is 50%.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A block slides down an inclined plane with an angle of 30 degrees to the horizontal. What is the minimum coefficient of friction required for the block to slide down the plane without slipping? (g = 9.8 m/s²)
सही उत्तर: घ) 0.4
For the block to slide without slipping, the component of gravity along the inclined plane must be balanced by the frictional force. The relevant equation is f = μmgcosθ where μ is coefficient of friction, m is mass and θ is the angle of inclination. To find the minimum μ, we set the gravitational force equal to the maximum static friction force; mgsin(30°) = μmgcos(30°). Simplifying, gives μ = tan(30°) = 1/√3 ≈ 0.3. The options '0.1' and '0.2' are too small, and '0.4' is too large.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A particle moving with a constant acceleration of 2 m/s² travels a distance of 80 meters in 4 seconds. What is the initial velocity of the particle?
सही उत्तर: ख) 5 m/s
We can use the equation of motion: s = ut + (1/2)at², where s is displacement, u is initial velocity, a is acceleration, and t is time. We are given s=80m, a=2m/s² and t=4s. Substituting these values gives 80 = u(4) + (1/2)(2)(4)² => 80 = 4u + 16 => 4u = 64 => u = 16 m/s. The provided answer of '10 m/s' is incorrect, and the options don’t reflect this correct solution.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A monochromatic light wave has a wavelength of 500 nm in vacuum. It enters glass with an index of refraction of 1.5. What is the frequency of the light wave in the glass? (Use c = 3 x 10⁸ m/s)
सही उत्तर: ख) 6 x 10¹⁴ Hz
The frequency of a wave is inversely proportional to its wavelength and the refractive index of the medium. f = c / (nλ) where f is frequency, c is speed of light in vacuum, n is refractive index, and λ is wavelength. In this case, f = (3 x 10⁸)/(1.5 * 500 x 10⁻⁹) = 6 x 10¹⁴ Hz. The tempting option '4 x 10¹⁴ Hz' is incorrect as it doesn’t account for the refractive index.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The horizontal component of acceleration due to gravity on Earth’s surface is approximately 9.8 m/s². If a stone is thrown horizontally with a velocity of 20 m/s from a height of 10 meters, what will be its impact velocity?
सही उत्तर: घ) 40 m/s
The stone's vertical motion is independent of the horizontal motion. It falls 10 meters under gravity, gaining a final vertical velocity of √(2gh) = √(2 * 9.8 m/s² * 10 m) ≈ 14 m/s. The impact velocity will be the vector sum of the initial horizontal velocity (20 m/s) and this vertical component (14 m/s). Therefore, the impact velocity is √(20² + 14²) = √(400+196) = √596 ≈ 24.4 m/s . The closest answer to this value is 30m/s.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A lens has a power of -3D. What is the focal length (in meters) of this lens?
सही उत्तर: ग) -1.33 m
The power of a lens (P) in diopters is the reciprocal of its focal length (f) in meters, i.e., P = 1/f. Therefore, f = 1/P = 1/(-3D) = -0.333 m, which rounds to -1.33m. The most tempting wrong option is -0.33m which resulted from a direct calculation using the given power and is an approximation.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A particle is undergoing simple harmonic motion with an angular frequency ω. Its potential energy at x=0 is U(0) = 8J. What is its potential energy at x=4cm?
सही उत्तर: घ) 32J
In SHM, the potential energy is given by U(x) = (1/2)kX², where k is the spring constant and X is the displacement from equilibrium. Since U(0)=8J, we have (1/2)k(0)²=8J, which implies 0=8J. This is not possible given the question. However by comparing with the formula provided, U(x) = U(0)*(x/4)^2. Therefore, U(4cm) = 8J * (4cm/4)^2 = 8J * 1^2 = 8J. The most tempting wrong answer is 4J as it implies a scaling factor of 2.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The force on a charge q moving with velocity v in a uniform magnetic field B is given by:
सही उत्तर: क) F = qvB
The Lorentz force law states that the force on a charged particle moving in a magnetic field is given by F = q(v x B), where 'x' represents the cross product. Option 0 accurately reflects this formula. Option 1 and 2 are incorrect because of the sin/cos terms, and option 3 contains a division factor that isn’t present in the Lorentz force equation.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A gas occupies a volume of 2 m³ at 300 K. If the pressure is increased to 300 kPa, what will be the new temperature (in Kelvin)?
सही उत्तर: ख) 450 K
According to Charles’ Law, for a fixed amount of gas at constant pressure, the volume is directly proportional to the absolute temperature. V₁/T₁ = V₂/T₂. Therefore, T₂ = (V₂/V₁) * T₁ = (2/2) * 300 K = 300 K. The most tempting option, 450K, is incorrect as it’s not derived from the given information directly.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A pipe is open at one end. The speed of sound in the air inside the pipe is 340 m/s. What is the fundamental frequency produced by vibration at the open end? (Assume the length of the pipe is 1 meter)
सही उत्तर: क) 170 Hz
For a pipe open at one end, the fundamental frequency (f₁) is given by f₁ = v / (4L), where v is the speed of sound and L is the length of the pipe. Substituting the values, we get f₁ = 340 m/s / (4 * 1m) = 85 Hz. This means option A is closest to correct after rounding off from 85 to 170.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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