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 force of 10 N acts on a mass of 2 kg at an angle of 30 degrees with the horizontal. What is the vertical component of this force?
सही उत्तर: क) 8.66 N
The vertical component of a force can be calculated using sin(θ), where θ is the angle with the horizontal. sin(30°) = 0.5, so the vertical component is 10 * 0.5 = 5N. The correct answer is included amongst options but it's a subtle mistake as the question asks for the ‘vertical’ component which is not simply the force value - we must multiply by sin(30). The other option are incorrect because they either use the wrong angle or fail to calculate the vertical component properly.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The speed of sound in air is approximately 343 m/s. If the temperature is 20°C, what is the speed of sound in m/s?
सही उत्तर: ख) 343
The speed of sound in air is directly proportional to the square root of the absolute temperature. The options provided list speeds that are close to 343 m/s, which is a reasonable approximation at 20°C. The other options are significantly higher or lower and therefore incorrect.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A light bulb emits electromagnetic waves with a frequency of 5 × 10¹⁴ Hz. What is the energy of a single photon emitted by the bulb? (Given: Planck’s constant h = 6.626 × 10⁻³⁴ Js)
सही उत्तर: क) 3.34 x 10⁻²⁰ J
The energy of a photon is given by E = hf, where h is Planck’s constant and f is the frequency. Plugging in the values, we get E = (6.626 × 10⁻³⁴ Js) * (5 × 10¹⁴ Hz) = 3.313 x 10⁻²⁰ J. The closest option is 3.34 x 10⁻²⁰ J.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The power dissipated in a circuit with voltage V and current I is given by:
सही उत्तर: ख) VI
Power (P) is defined as the rate at which energy is transferred, i.e., P = VI. The other options involve square roots or squares of V and I, which are not the standard definition of power in a simple circuit.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A ball is thrown vertically upwards with an initial velocity of 20 m/s. Neglecting air resistance, what will be its velocity just before it returns to the same height?
सही उत्तर: ख) 20 m/s
The final velocity will be equal in magnitude but opposite in direction to the initial velocity. Using v² = u² + 2as, with a = -g (acceleration due to gravity), we get v² = 20² + 2(-10)t², where t is the time of flight. The tempting incorrect option of 40 m/s doesn't account for the negative acceleration.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The force required to move a mass of 10 kg across a surface with a coefficient of kinetic friction of 0.2 N/kg is approximately:
सही उत्तर: घ) 40 N
Force = Friction Force = μ * N, where μ is the coefficient of kinetic friction and N is the normal force. The normal force equals the weight of the object (mg), so Force = 0.2 * 10 * 10 = 20N. Option 9.8N is too small, 40N is much larger.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A body slides down a frictionless inclined plane of length ‘l’ and height ‘h’. The acceleration due to gravity is ‘g’. What is the final velocity of the body at the bottom of the incline?
सही उत्तर: क) 10 m/s
The final velocity can be calculated using the kinematic equation v² = u² + 2as, where v is the final velocity, u is the initial velocity (0 in this case), a is the acceleration due to gravity (g), and s is the distance (l) along the incline. The most tempting incorrect option is 5 m/s as it’s a random value.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a Wheatstone bridge circuit with resistances P, Q, R and S, what condition must be met for balance to occur?
सही उत्तर: ख) P/Q = R/S
For a Wheatstone bridge to be balanced, the ratio of the resistances must be equal on both sides of the bridge. Specifically, the ratio of P to Q must be equal to the ratio of R to S. This condition ensures that no current flows through the galvanometer (the null point is achieved).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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If the distance between two masses is doubled while their combined mass remains constant, what happens to the gravitational force between them?
सही उत्तर: ग) It quadruples
According to Newton's Law of Universal Gravitation, the gravitational force (F) is directly proportional to the product of the masses (m1 and m2) and inversely proportional to the square of the distance (r) between them: F = G * (m1 * m2) / r². If the distance doubles (r becomes 2r), the force becomes F = G * (m1 * m2) / (2r)² = G * (m1 * m2) / 4r², which is one-quarter of the original force.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A 12V battery with an internal resistance of 1Ω is connected to an external resistor of 5Ω. What is the current flowing through the circuit?
सही उत्तर: घ) 2.0 A
Using Ohm's law (V = IR), we can calculate the current: I = V/R = 12V / 5Ω = 2.4 A. However, due to the internal resistance of the battery, the actual current is slightly less than calculated as a result of the voltage drop across the internal resistance. The closest option and most accurate solution will be represented by 2.0A.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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