भौतिक विज्ञान – Physics MCQ
भौतिक विज्ञान – IT प्रवेश
Physics · IT Entrance – B.Sc. CSIT, BIT & BCA · ३९१ प्रश्न
३९१ 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 ball rolls without slipping down a slope. If the angle of inclination of the slope is θ, then the acceleration of the ball along the slope will be (g = गुरुत्वीय त्वरण):
सही उत्तर: क) g sin θ
The correct answer is g sin θ. This is due to component of gravity acting down the slope, causing a downward acceleration. The other options are incorrect because they don't account for the ball rolling without slipping; cos θ represents the perpendicular component and 0 represents no force.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A cylindrical wire has a length L and a radius R. If the resistivity of the material is ρ, what is its resistance (R)?
सही उत्तर: ख) ρL/(πR²)
The resistance of a wire is given by R = ρL/A, where ρ is resistivity, L is length and A is the cross-sectional area. For a cylindrical wire, the area is πR². Therefore, R = ρL/(πR²). Option 2 is incorrect because it uses the wrong formula. Option 3 doesn’t correctly account for the radius of the wire.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A uniform solid sphere of mass M and radius R is rotating with an angular velocity ω about its central axis. What is the kinetic energy (KE) of the sphere?
सही उत्तर: क) (1/2)MRω²
The rotational kinetic energy of a solid sphere is given by KE = (1/2)Iω², where I is the moment of inertia. For a uniform solid sphere rotating about its diameter, I = (2/5)MR². Therefore, KE = (1/2)*(2/5)MR²ω² = (1/5)MR²ω². The tempting answer MR³ω²/(3*2) misinterprets the moment of inertia and doesn't correctly use the formula.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Two sound waves with intensities I₁ and I₂ are incident on a surface. When they interfere constructively, the intensity of the resulting wave is 4I₁. What is the phase difference between the two waves?
सही उत्तर: घ) π radians
Constructive interference occurs when the waves are in phase (i.e., their phases differ by an integer multiple of 2π). The new intensity is I = I₁ + I₂ = 4I₁. This implies that I₁ and I₂ must be out of phase by π/3 radians (2π/3) to achieve this result, otherwise the equation wouldn’t hold true. Options 0 degrees or 0 radians represent perfect synchronization.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A body of mass 2 kg is projected vertically upwards with an initial velocity of 10 m/s. What will be its speed when it returns to the same height?
सही उत्तर: घ) 0 m/s
The correct answer is 5 m/s. Ignoring air resistance, the body's kinetic energy will be converted into potential energy at its highest point and back again. The final speed will be equal to the initial velocity in magnitude but opposite in direction. Using conservation of energy: KE (initial) = PE (at max height) + KE (final). The key is recognizing that it’ll return with the same speed, just moving downwards.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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What is the SI unit for power?
सही उत्तर: क) Watt
The correct answer is Watt. Power, defined as the rate at which energy is transferred or converted, is measured in Watts (W), where 1 W = 1 J/s. Joule represents energy; Newton represents force and Kilogram represents mass.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A wave travels along a stretched string. Which of the following properties determines the speed of the wave?
सही उत्तर: ग) The tension in the string and its linear density.
The correct answer is option 2. The speed (v) of a wave on a stretched string is determined by the equation v = √(T/μ), where T is the tension in the string, and μ is the linear mass density (mass per unit length). Options 1 and 3 describe factors influencing wave speed; Amplitude is a characteristic of the wave disturbance.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The acceleration due to gravity (g) on Earth is approximately 9.8 m/s². Which of these best describes the effect of increasing the height from which an object is dropped?
सही उत्तर: ग) No change in the final velocity of the object (neglecting air resistance).
The correct answer is option 2. According to the principle of conservation of energy, an increase in the height from which an object is dropped results in an increase in its potential energy. This increased potential energy is converted into kinetic energy as the object falls, leading to a higher final velocity before impact. Option 1 describes initial velocity change; option 3 is correct assuming negligible air resistance and option 4 refers to falling time.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The power dissipated in a series circuit consisting of a 6Ω resistor and a capacitor of 2μF connected to a 12V DC source is (ε = 12 V, R = 6 Ω, C = 2 μF).
सही उत्तर: ख) 2. 72 W
The impedance of the capacitor in DC is Zc = 1/jωC, where j is the imaginary unit and ω is the angular frequency (ω = 2πf). The power dissipated is P = V² / R = 12² / 6 = 288 / 6 = 48 W. However, this value needs to be revised as it's not in the given options. A correct analysis of the circuit involves calculating the current and then the power dissipation across the resistor.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The refractive index of a glass is 1.5. A ray of light enters this glass from air. If the angle of incidence is 30°, what is the angle of refraction?
सही उत्तर: ख) 2. 60°
The Snell's law states n₁sinθ₁ = n₂sinθ₂ where n₁ and n₂ are the refractive indices of air and glass respectively, and θ₁ and θ₂ are the angles of incidence and refraction. Here, n₁=1, θ₁=30°, and n₂=1.5. Solving for θ₂, we get sinθ₂ = (1.5*sin30°) / 1 = 0.75 so θ₂ ≈ 46.4° which is closest to 50°. The other options are clearly incorrect.
💬 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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