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 kinetic energy of a particle moving with velocity 'v' is given by KE = (1/2)mv². If the velocity doubles, what happens to the kinetic energy?
सही उत्तर: ख) It is doubled
According to the equation of kinetic energy, it’s directly proportional to the square of the velocity. Doubling the velocity results in a four-fold increase in kinetic energy (KE = (1/2) * 2m * v² = 2 * (1/2)mv² = KE). The most tempting answer is doubled, which is incorrect.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A uniform wire of length L and cross-sectional area A is connected to a battery. If the resistance of the wire is R, what is the ratio of A to L?
सही उत्तर: क) 1/R
The resistance (R) of a wire is given by R = ρL/A, where ρ is the resistivity. The correct answer is R/A, because we are looking for the ratio between area and length which will cancel out the resistivity to give the resistance.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A metal rod is heated from 20°C to 80°C. If the linear expansion of the rod is 0.0015 per °C, what will be the fractional change in its length?
सही उत्तर: क) 0.01
The fractional change in length (ΔL/L) is given by α * ΔT, where α is the coefficient of linear expansion and ΔT is the change in temperature. Therefore, ΔL/L = 0.0015 * (80°C - 20°C) = 0.0015 * 60 = 0.09. However, this value is not among the options. The closest answer which would be produced by a mistake in calculation of α is 0.04, but with accurate use of α and ΔT, the actual fractional change will be far greater than that.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A transformer has a primary coil with 500 turns and a secondary coil with 100 turns. If the voltage in the primary coil is increased by 10%, what is the percentage increase in the voltage in the secondary coil?
सही उत्तर: क) 10%
The ratio of voltages in a transformer is equal to the ratio of the number of turns. So, V_secondary / V_primary = 100/500 = 0.2. Therefore, V_secondary = 0.2 * V_primary. A 10% increase in V_primary results in a 20% increase in V_secondary (0.2 * 1.1 = 0.22).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The density of water is 1000 kg/m³ and its specific gravity is 0.5. What is its apparent weight of a 2kg object submerged in water? (Take g = 9.8 m/s²).
सही उत्तर: क) 9.8 N
The apparent weight is the buoyant force, which equals the weight of the water displaced. The volume of the object is V = mass/density = 2kg / 1000 kg/m³ = 0.002 m³. The buoyant force is then F_b = density * volume * g = 1000 kg/m³ * 0.002 m³ * 9.8 m/s² = 19.6 N.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A battery of 12V delivers a current of 2 Amperes to a circuit. What is the power dissipated in the circuit?
सही उत्तर: क) 24 W
Power (P) is calculated using P = V * I, where V is voltage and I is current. Therefore, P = 12V * 2A = 24W. The other options are incorrect calculations of the power given different values for the battery or current.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A light ray traveling from air into water is refracted. Which of the following statements accurately describes this phenomenon?
सही उत्तर: घ) The light ceases to travel through water
When a ray of light passes from one medium (air) to another (water), its speed changes. This change in speed causes the ray to bend, or refract. The bending occurs because the wave nature of light dictates that it travels at different speeds in different media. Snell's law governs this behavior – the angle of incidence equals the angle of refraction when the refractive indices are equal. Options 1 & 2 are incorrect as they state the speed increases or use incorrect angles. 2023
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A car accelerates uniformly from rest to a velocity of 36 km/h in 10 seconds. What is the acceleration of the car?
सही उत्तर: ख) 3.6 m/s²
First, convert the final velocity to meters per second: 36 km/h = (36 * 1000) / 3600 m/s = 10 m/s. Using the equation v = u + at (where v=final velocity, u=initial velocity, a=acceleration, t=time), we have 10 = 0 + a*10, so a = 1 m/s². However, the question asks for acceleration, which is equal to change in velocity over time. Thus, Acceleration = (change in velocity) / time. Here Change in Velocity = final - initial = 10-0=10 m/s and Time = 10 sec, so acceleration would be 10m/s/10sec = 1 m/s^2. There is a misinterpretation of the formula used (the correct one is v=u+at). However, as the question asks for acceleration, we can find it using Δv/t = (10-0)/10=1m/s^2. This needs to be modified to fit the given values. 2023
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following statements best describes the phenomenon of total internal reflection?
सही उत्तर: ग) Light reflects back into a denser medium from a less dense medium at an angle equal to or greater than the critical angle
Total internal reflection occurs when light travels from a denser medium (e.g., glass) to a less dense medium (e.g., air) and the incident ray is within the core of the material. The angle of incidence exceeds the critical angle, causing total reflection. Diffraction and sound wave reflections are different phenomena. 2023
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A uniform beam of length L is placed on a rough horizontal surface. A force F is applied perpendicular to the beam at its center. If the coefficient of static friction between the beam and the surface is μ, what is the maximum value of F that will cause the beam to just start moving?
सही उत्तर: ख) F = μL
For the beam to move, the frictional force must equal the applied force. The frictional force is given by f = μN, where N is the normal reaction (in this case, F/2). Therefore, F = μ(F/2), which simplifies to F = μL. Options F=2μL and F=∞ are incorrect as they require excessive forces or no friction at all. 2023
💬 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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