भौतिक विज्ञान – Physics MCQ
भौतिक विज्ञान – कृषि/वन प्रवेश
Physics · Agriculture, Veterinary & Forestry Entrance · ४२५ प्रश्न
४२५ प्रश्न उपलब्ध। मोड छान्नुहोस्:
भौतिक विज्ञान: 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 body falls freely from a height ‘h’. The velocity of the body just before striking the ground is:
सही उत्तर: क) √(gh)
According to the principle of conservation of energy, the potential energy at height 'h' is converted into kinetic energy just before impact. KE = mgh, so the velocity is √(gh). The other options reflect incorrect application of physics principles.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The potential energy stored in a capacitor with capacitance C and charged to a voltage V is given by:
सही उत्तर: क) CV
Potential energy (PE) stored in a capacitor is given by the formula PE = CV. This directly represents the product of charge (Q=CV) and voltage. The other options are incorrect formulas or misinterpretations of capacitance.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A monochromatic light beam is incident on a single slit of width 'd'. The wavelength of light is λ and the angle of diffraction is θ. Which of the following statements correctly relates the two?
सही उत्तर: ग) θ = 2d/λ
The principle of diffraction dictates that the angle of diffraction (θ) for a single slit is given by θ = ( λ / d ) where λ is the wavelength and d is the width of the slit. Option 2 accurately represents this relationship.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The velocity of sound in air at a given temperature is 340 m/s. If a person hears the echo of a shout after throwing a stone, what distance to the reflecting surface has the stone traveled?
सही उत्तर: घ) 1020m
The echo is heard after the sound wave travels to the reflecting surface and back. This means the stone travelled twice the distance to the surface. Therefore, the total distance = 2 * 340 m = 680 meters.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A radioactive element has a half-life of 10 years. What fraction of the original amount will remain after 20 years?
सही उत्तर: ख) 1/4
The half-life is the time it takes for half of the material to decay. After one half-life (10 years), half remains. After two half-lives (20 years), half of that remaining half, or 1/4 of the original amount, will remain. Thus, the answer is 1/4.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following statements correctly describes the relationship between potential energy (PE) and kinetic energy (KE)?
सही उत्तर: ग) PE is inversely proportional to KE
Potential energy represents stored energy due to position or configuration, while kinetic energy represents the energy of motion. The relationship between them is that PE is proportional to KE; a change in height (affecting potential energy) results in an equal and opposite change in speed (affecting kinetic energy). The other options are incorrect representations of these concepts.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A particle is moving with a velocity ‘v’ at an angle θ to the horizontal. At a certain instant, its velocity is reduced to ‘v/2’ perpendicular to the initial direction of motion. What was the initial speed ‘v’? (Assume no other forces are acting on the particle.)
सही उत्तर: ग) 3 m/s
The particle's velocity is reduced from 'v' to 'v/2' perpendicularly, meaning it experienced a change in direction. This indicates that the initial velocity was at least 'v/2', which would allow for this perpendicular motion. 2 m/s corresponds to v/2 and then v.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The acceleration due to gravity ‘g’ decreases with increasing altitude. Approximately by what percentage does ‘g’ decrease if a person climbs to an altitude of 1 km above sea level? (Assume g at sea level is 9.8 m/s² and the Earth's radius is approximately 6400 km.)
सही उत्तर: ख) 10%
The acceleration due to gravity decreases with altitude because the gravitational force weakens as you move further away from the center of the Earth. This reduction in force results in a decrease in ‘g’. A change of 10% aligns with the expected rate of decreasing g over approximately 1 km elevation, while the others are less accurate approximations.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The phenomenon of refraction of light occurs when:
सही उत्तर: ख) Light passes from one medium to another with different densities
Refraction is defined as the bending of light when it transitions between media with differing refractive indices. This occurs due to changes in the speed of light within those mediums. The other options describe different optical phenomena.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A uniform rod of length L and mass M is placed in equilibrium on a rough horizontal surface. The coefficient of friction between the rod and the surface is μ. What is the force applied horizontally to maintain equilibrium?
सही उत्तर: ख) 2M/μ
The forces acting on the rod are gravity (Mg downwards), the normal reaction from the surface (N upwards), and the frictional force (f = μN sideways). To be in equilibrium, the horizontal component of the applied force must balance the frictional force. Therefore, F_horizontal = f = μN.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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