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 stone is thrown horizontally from the top of a cliff with an initial velocity of 20 m/s. The height of the cliff is 50 meters. Ignoring air resistance, what is the horizontal distance traveled by the stone before it hits the ground? (Use g = 9.8 m/s²)
सही उत्तर: ख) 30m
The stone's initial velocity and height determine its range. We can use the equations of motion to calculate the time it takes for the stone to fall 50 meters, then multiply that time by the horizontal velocity. Option A (10m) is incorrect as it doesn’t account for vertical displacement. Option C (50m) is wrong as the height isn't directly equal to the range in this scenario.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A particle moves with a velocity vector v = (3i + 4j) m/s. Its kinetic energy is:
सही उत्तर: क) (a) 30 W/m²
Intensity (I) is defined as power (P) per unit area (A): I = P/A. The bulb emits radiation equally in all directions, so the area of the sphere at a distance 'r' from the bulb is 4πr². Thus, I = P / (4πr²). With P = 60 W and r = 1 m, I = 60 W / (4π(1)² ) ≈ 4.73 W/m², which is not among the choices. We can assume there may have been an error in options provided.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The refractive index of a medium is defined as the ratio of (a) Velocity of light in vacuum to velocity of light in the medium (b) Velocity of light in the medium to velocity of light in vacuum (c) Angle of incidence to angle of refraction (d) Refractive angle to critical angle.
सही उत्तर: ख) (b) Velocity of light in the medium to velocity of light in vacuum
The refractive index (n) is indeed defined as the ratio of the speed of light in a vacuum (c) to the speed of light in the medium (v): n = c/v. Option (b) correctly reflects this definition. The other options represent different optical phenomena or angles.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The energy of a photon with a frequency of 6.63 × 10⁻³⁴ J s is 2.91 x 10⁻¹⁹ joules. What is the frequency of this photon?
सही उत्तर: ख) 3.0 × 10¹⁴ Hz
The energy of a photon is given by the equation E = hf, where E is energy, h is Planck's constant (6.63 x 10⁻³⁴ J s), and f is frequency. Option 1 calculates correctly: (6.63 × 10⁻³⁴ J s) * (1.5 × 10¹⁴ Hz) = 2.91 x 10⁻¹⁹ joules. The other options result in significantly different energy values.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The average frictional force acting on a vehicle moving at 30 m/s with a deceleration of 2 m/s² over a distance of 150 meters is calculated using Newton’s second law. What is this force in Newtons?
सही उत्तर: ख) 900 N
Newton's Second Law states F = ma. Here, m=800 kg and a = -2m/s². Therefore, F = 800kg * (-2m/s²) = -1600 N. The absolute value of this force is 1600N, but since the question asks for the average frictional force, we must calculate it based on initial velocity and final velocity. The other options are incorrect as they don't apply to the given values.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The potential difference across a capacitor is doubled. What happens to its charge?
सही उत्तर: ख) It doubles
According to the formula Q = CV, where Q is charge, C is capacitance and V is potential difference, if V doubles, then Q also doubles while C remains constant. The other options incorrectly relate changes in voltage to charge.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A metal rod has a length of 1 meter and cross-sectional area of 0.001 m². If the resistance of the rod is 10 ohms, what is its resistivity in ohm-meters?
सही उत्तर: क) 10
Resistivity (ρ) is defined as R * A / L, where R is resistance, A is cross-sectional area, and L is length. Therefore, ρ = 10 ohms * 0.001 m² / 1 meter = 0.01 ohm-meters. The other options do not correctly calculate the resistivity using the given values.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A car travels at a uniform speed of 60 km/h for 2 hours and then at a uniform speed of 80 km/h for 3 hours. What is the average speed of the car during the entire journey?
सही उत्तर: ग) 72.5 km/h
The total distance traveled is (60 * 2) + (80 * 3) = 120 + 240 = 360 km. The total time taken is 2 + 3 = 5 hours. Average speed = Total Distance / Total Time = 360 km / 5 hours = 72 km/h. The other options are calculated incorrectly.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The resistance of a wire is directly proportional to its length and inversely proportional to its area of cross-section. If the resistance of a wire of length L and area A at 20°C is R Ω, and its length is increased to 2L while keeping the area constant, what will be the new resistance?
सही उत्तर: घ) R/4
According to the given relationship, R = (ρL/A), where ρ is a constant. If L becomes 2L and A remains the same, then the new resistance will be (ρ * 2L) / A = 2 * (ρL/A) = 2R. The other options result from incorrectly applying proportionality.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A sound wave has a frequency of 440 Hz and wavelength 1.76 m. What is its speed in meters per second?
सही उत्तर: ख) 880 m/s
The speed of sound (v) is calculated using the formula v = fλ, where f is the frequency and λ is the wavelength. Substituting the given values: v = 440 Hz * 1.76 m = 880 m/s. The other options are incorrect because they do not correctly apply this fundamental wave equation.
💬 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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