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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The principle of conservation of energy states that:
सही उत्तर: ग) c) The total amount of energy in an isolated system remains constant.
Option (c) accurately reflects the principle. In a closed system, energy transforms from one form to another (e.g., potential to kinetic), but the total amount never changes.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A student measures the period of oscillation of a simple pendulum with length 1 meter. He obtains values for ‘T’ (period) as 1.2 s, 1.5 s, and 1.8 s. What is the best estimate of the period, considering the experimental error?
सही उत्तर: ख) 1.5 s
To minimize the impact of random errors, we calculate the average of the given values: (1.2 + 1.5 + 1.8) / 3 = 4.5 / 3 = 1.5 s. This is the most central value among the possible answers.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A transparent plastic block is partially immersed in a liquid. The light rays bend towards the normal when passing through the block. What does this indicate about the refractive index of the plastic relative to the liquid?
सही उत्तर: क) Plastic’s refractive index > Liquid’s refractive index
When light passes from one medium to another, it changes speed and direction. The bending of light towards the normal indicates that the plastic has a higher refractive index than the liquid – this means it travels slower in the plastic compared to the liquid. The options about pressure are irrelevant to refraction.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A ball of mass 0.5 kg is dropped from a height of 10 meters above the ground. Assuming no air resistance, what will be its velocity just before it hits the ground?
सही उत्तर: घ) 20 m/s
We can use the principle of conservation of energy to solve this problem. The initial potential energy (PE) is mgh, where m = 0.5 kg, g = 9.8 m/s², and h = 10 m. At the instant before impact, all PE is converted into kinetic energy (KE), given by KE = 1/2 mv². Therefore, mgh = 1/2 mv² so v = √(2gh) = √(2 * 9.8 * 10) ≈ 14.35 m/s - the closest answer is 15m/s due to rounding.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A wire carrying a current of 3 A experiences a magnetic force of 6 N when passing through a magnetic field of 2 Tesla at an angle of 60 degrees. What is the length of the wire?
सही उत्तर: घ) 4 m
We can use the formula for magnetic force: F = I L Sin θ, where F is the force in Newtons, I is the current in Amperes, L is the length in meters, and θ is the angle between the wire and the magnetic field. Solving for L, we get L = F / (I Sin θ) = 6 N / (3 A * Sin 60°). Calculating this gives us approximately 3 m.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The electric field intensity at a point 'P' near a charge ‘Q’ is E. If the distance from P to the charge Q is doubled, what will be the new electric field intensity?
सही उत्तर: ख) E/4
The relationship between electric field intensity (E), charge (Q) and distance (r) is E = kQ/r², where k is a constant. If r is doubled, then r² becomes four times greater. Therefore, the new electric field intensity will be kQ/(4r) which simplifies to E/4. The option E/2 is incorrect because doubling only affects the distance squared and not by a factor of 2. Increasing the distance by a factor of two would halve the electric field strength.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A student connects a 2V cell to a galvanometer. The galvanometer shows no deflection. What additional component must be connected in series with the cell and galvanometer to make the galvanometer deflect?
सही उत्तर: क) A resistance
Galvanometers measure small currents. To get a deflection when connected to a cell, we need to reduce the current flowing through the galvanometer. A resistor in series will do this and allow a measurable current.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The de Broglie wavelength (λ) of a particle is given by λ = h/p, where h is Planck’s constant and p is momentum. If a particle has a momentum ‘p’, what is its de Broglie wavelength?
सही उत्तर: क) h/p
The formula for the de Broglie wavelength is directly given as λ = h/p. Therefore, when momentum 'p' is known, its corresponding wavelength is 'h/p'.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The period of revolution of a geostationary satellite is approximately 24 hours. What is its orbital radius relative to Earth’s surface?
सही उत्तर: घ) 72,000 km
A geostationary satellite orbits at an altitude of approximately 36,000 kilometers above the Earth’s surface. At this altitude, its orbital period matches the Earth's rotation, thus maintaining a fixed position relative to observers on Earth.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A ball is thrown upwards in the air with an initial velocity of 20 m/s. Assuming g = 9.81 m/s², what is the maximum height reached by the ball? (Use 10 m = 1 km)
सही उत्तर: ख) 7 km
The maximum height is reached when the final velocity of the ball is zero. Using kinematics equation v² = u² + 2as (where v=0, u=20 m/s, a=-9.81 m/s², and s is the height), we can solve for s to find the maximum height.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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