भौतिक विज्ञान (Physics) – Physics MCQ
भौतिक विज्ञान (Physics) – CEE प्रवेश
Physics · Medical Entrance (CEE) – Physics, Chemistry, Biology & MAT · ४०७ प्रश्न
४०७ प्रश्न उपलब्ध। मोड छान्नुहोस्:
भौतिक विज्ञान (Physics): 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 uniform magnetic field of 0.5 Tesla points in the positive z-direction. If a charge particle with a charge of +2 μC enters this field with a velocity of 300,000 rad/s along the negative z-direction, what will be the magnitude of the force acting on it?
सही उत्तर: क) 1.5 N
The Lorentz force equation is F = qvBsinθ, where q is the charge, v is the velocity, B is the magnetic field strength, and θ is the angle between the velocity and the magnetic field vectors. Here, v=300,000 rad/s, B=0.5T and the velocity is along the negative z-direction, so θ = 90 degrees; sin(90°) = 1. Thus, F = (2 x 10^-6 C)(300,000 rad/s)(0.5 T) = 3 N. Options A, C and D are incorrect.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The coefficient of linear expansion of a metal is 0.001 per degree Celsius. If a rod of iron with length 1 meter at 20°C is heated to 100°C, what will be the increase in its length? (Take β = 0.001)
सही उत्तर: ख) 0.3 m
The change in length (ΔL) is given by ΔL = αL₀ΔT, where α is the coefficient of linear expansion, L₀ is the original length, and ΔT is the change in temperature. Substituting the values: ΔL = 0.001 * 1 m * (100°C - 20°C) = 0.3 m.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The potential difference across a capacitor is doubled. Assuming the capacitance remains constant, what happens to the charge on the capacitor? (a) It remains unchanged (b) It is halved (c) It is doubled (d) It is quadrupled
सही उत्तर: ग) It is doubled
According to the equation Q = CV (where Q is charge, C is capacitance, and V is potential difference), if V doubles and C stays the same, then Q must also double.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A transformer has 100 turns in the primary coil and 200 turns in the secondary coil. If the voltage of the primary coil is reduced from 220 V to 110 V, the voltage of the secondary coil will be: (a) 110 V (b) 220 V (c) 440 V (d) 550 V
सही उत्तर: क) 110 V
Transformers operate on the principle of electromagnetic induction. The ratio of turns is inversely proportional to the ratio of voltages. Therefore, if the primary voltage decreases by a factor of 2, the secondary voltage also decreases by a factor of 2.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A particle of mass m is attached to a fixed wall by a rope of length l, with the rope making an angle θ with the vertical. The tension in the rope is: (a) mg (b) mlg cosθ (c) mlg sinθ (d) 0
सही उत्तर: घ) 0
The forces acting on the particle are tension in the rope and the wall's normal force. Since the rope is tangent to the circle, the tension provides the centripetal force. Therefore, the tension is mlg sinθ.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The kinetic energy of a simple harmonic oscillator at its mean position is: (a) Zero (b) Equal to the potential energy (c) Maximum (d) Half of the potential energy
सही उत्तर: क) Zero
At the mean position, all the oscillator’s energy is stored as potential energy. Options (b), (c) and (d) describe a point where kinetic energy is present; therefore, zero represents the correct answer.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A beam of light passes from air into glass at an angle of incidence of 30 degrees. The refractive index of glass is 1.5. What is the angle of refraction?
सही उत्तर: ग) (c) 60 degrees
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. In this case, n₁ = 1, n₂ = 1.5, and θ₁ = 30°. Therefore, sinθ₂ = (n₂/n₁)sinθ₁ = (1.5/1)sin30° = 1.5 * 0.5 = 0.75. Thus, θ₂ = arcsin(0.75) ≈ 45 degrees. Option (a) is incorrect because it’s half the correct angle.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The magnetic field at a point P due to an infinite current-carrying wire is perpendicular to the direction of the wire. If the distance between the wire and the point P is doubled, what happens to the magnetic field strength at point P?
सही उत्तर: घ) (d) Decreases by a factor of 2
The magnetic field strength due to an infinite wire is given by B = μ₀I/r, where r is the distance from the wire. If the distance ‘r’ doubles (becomes 2r), then the new magnetic field strength becomes B' = μ₀I/(2r) = (1/2) * (μ₀I/r) = (1/2)B. Therefore, the magnetic field strength decreases by a factor of 2. Option (a) is incorrect as it doesn't account for distance.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A capacitor consists of two parallel plates separated by an air gap. If the dielectric material between the plates is replaced with a rubber sheet having a dielectric constant of k = 3, what will be the capacitance?
सही उत्तर: घ) (d) Depends on the area and distance only
When a dielectric material with a dielectric constant ‘k’ is inserted between the plates of a capacitor, the capacitance increases. The new capacitance (C’) becomes C’ = k * C, where C is the original capacitance. Thus, the correct option is (c). Using the formula C=ε₀A/d, we replace ε₀ with ε₀k to find the increased capacitance.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The period of oscillation of a simple pendulum is given by T = 2π√(L/g), where L is the length and g is the acceleration due to gravity. If the length of the pendulum is increased by 20% and the gravitational acceleration remains constant, what is the percentage change in its period?
सही उत्तर: ख) (b) 20% decrease
The new period will be T' = 2π√(L’/g), where L’ = 1.2L. Therefore, T’/T = √(1.2/1) = √1.2 ≈ 1.095. This represents a 9.5% increase over the original period, closest to 10%. Hence the correct answer is (a). Option (b) is incorrect as it would result in a decrease.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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