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 refractive index of a glass slab is 1.5. A ray of light enters the slab at an angle of incidence of 30°. What is the speed of light in glass? (Take speed of light in vacuum as 3 x 10^8 m/s)
सही उत्तर: ख) 2.5 x 10^8 m/s
Refractive index (n) is the ratio of speed of light in vacuum (c) to the speed of light in the medium (v): n = c/v. Therefore, v = c/n = (3 x 10^8)/1.5 = 2 x 10^8 m/s. The most tempting incorrect answer is 3.5 x 10^8 because it uses a rounded value for the refractive index.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The speed of sound in air at room temperature is approximately 343 m/s. If a source emits sound waves with a frequency of 440 Hz, what is the wavelength of these sound waves?
सही उत्तर: क) 0.81 m
Wavelength (λ) is related to speed (v) and frequency (f) by the equation λ = v/f. Therefore, λ = 343m/s / 440Hz ≈ 0.78 m. The closest answer is 0.81 m which represents an approximate value resulting from rounding.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A uniform magnetic field of 0.5 T is applied perpendicular to the plane of a circular conductor of radius 0.1 m, carrying a current of 2 A. What is the force acting on a small section of this conductor?
सही उत्तर: क) 0.1 N
The force on a current-carrying wire in a magnetic field is given by F = I L B sinθ, where I is current, L is length of the wire, B is magnetic field strength and θ is the angle between them. For a small section, L ≈ r (radius) and θ=90 degrees. Therefore, F = 2A * 0.1m * 0.5T*sin(90°) = 0.1 N. The option of 0.5 N is incorrect because it uses the wire length incorrectly.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The force required to extend a spring by 0.1 m is 2 N. What is the stiffness (k) of the spring?
सही उत्तर: क) 0.2 N/m
Hooke's Law states F = kx, where F is force, k is stiffness, and x is displacement. Solving for k gives us k = F/x = 2N / 0.1m = 20 N/m. The tempting option of 0.2 N/m is incorrect because it doesn't account for the given force and distance.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The velocity of sound in air at room temperature (approximately 20°C) is approximately: (speed of sound in air at 0°C is 331.5 m/s and at 20°C is 343 m/s)
सही उत्तर: ख) 331.5 m/s
The speed of sound in air varies with temperature. The formula relating these two quantities is v = 331.5 + 0.6T, where T is the temperature in Celsius. Therefore, at 20°C, the speed is approximately 343 m/s. Options like 310 and 350 m/s are significantly different.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The power dissipated in a resistor is given by P = I²R and P = V²/R. Which equation correctly relates Power (P) to Voltage (V) and Resistance (R)?
सही उत्तर: ख) P = √IR
The correct relationship is derived from equating the two power equations: V² / R = I²R, which simplifies to P = V²/R. The other options are incorrect combinations of voltage and resistance.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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एकल पेन्डुलमको लांस ४ गुणा बढाउँदा उसको अवधि (time period) कस्तो हुन्छ?
सही उत्तर: क) 4 गुणा
The time period (T) of a simple pendulum is given by the formula T = 2π√(L/g), where L is the length and g is the acceleration due to gravity. If the length is increased four times (L' = 4L), then the new time period will be T' = 2π√(4L/g) = 2π√4 * √(L/g) = 4T, meaning it increases by a factor of 4.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A body slides down an inclined plane of angle θ with the horizontal. The coefficient of friction between the body and the plane is μ. What is the minimum value of θ for which the body will start sliding?
सही उत्तर: ख) 30°
The body will start sliding when the component of gravity along the inclined plane equals the friction force. This occurs when sin(θ) ≥ μcos(θ). The option 30° is correct because it represents the angle at which sin(θ) = μcos(θ) – a critical condition for initiating movement. Options 15°, 45° and 60° are incorrect as they don’t satisfy this equality.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The term ‘parallax’ is most closely associated with:
सही उत्तर: ख) b) Measuring distances to nearby stars by observing their apparent shift due to Earth's movement.
Option (b) is correct. Parallax uses the apparent shift in position of a star against the background when viewed from different locations to determine its distance.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A ball is thrown vertically upwards. At its highest point, what is its velocity?
सही उत्तर: ख) b) 0 m/s.
Option (b) is correct. At the highest point of its trajectory, the ball momentarily stops before it begins to fall back down; therefore, its velocity is zero relative to the ground.
💬 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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