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 wire of length L and cross-sectional area A is stretched by ΔL. If the Young's modulus for the material is Y, what is the stress applied on the wire? (Young's modulus = Y = T/ (AΔL) where T is tensile force)
सही उत्तर: क) T/(AΔL)
The question directly relates Young's modulus to stress and strain. The options propose various calculations, but the fundamental equation of Young’s modulus defines the relationship between these variables when a wire is stretched. Options 'A/L', ‘L/A’, and ‘ΔL/A’ are incorrect as they do not correctly use the definition of Young's Modulus.”}],
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A 100 g ice cube at 0°C is placed in a container containing 500g of water also at 0°C. The specific heat capacity of ice is 2.1 J/g°C and the specific heat capacity of water is 4.186 J/g°C. Assuming no heat is lost to the surroundings, what is the final temperature of the water?
सही उत्तर: ग) 30°C
This problem involves heat transfer and thermal equilibrium. The ice will melt first absorbing heat from the water until it reaches 0°C. Then, the melted ice (water) will absorb more heat from the water until both are at a uniform temperature. The heat gained by the ice = Heat lost by the water. Q_ice = m_ice * c_ice * ΔT; Q_water = m_water * c_water * ΔT, where m is mass, c is specific heat and ΔT is change in temp. The melting point of the ice happens at 0°C so that ΔT= T_final - 0 = T_final. Thus: m_ice*2.1*(T_final-0) = m_water *4.186 *(T_final-0). Simplifying gives: (100)(2.1) T_final = (500)(4.186) T_final => 210 T_final = 2093 T_final. This is wrong so let's rethink. Instead, we’ll consider the heat required to melt all ice into water at 0°C and then further heat the water until it reaches equilibrium temperature. The latent heat of fusion of ice is about 334 J/g, and the final equilibrium temperature will be approximately 20°C.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Two sound waves with amplitudes 2 cm and 3 cm respectively, are superposed. The resultant amplitude is 5 cm. What is the phase difference between the two waves?
सही उत्तर: ख) 90 degrees
The resultant amplitude of two overlapping sound waves is given by the principle of superposition: R = √(A₁² + A₂² + 2A₁A₂cos(θ)) where R is the resultant amplitude, A₁ and A₂ are the amplitudes of the individual waves and θ is the phase difference between the waves. For R to be maximum (5 cm), cos(θ) must be equal to 1, which means θ = 0 degrees. The tempting incorrect option of '90 degrees' arises from considering the potential for destructive interference when amplitudes are different.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A stone is dropped from the top of a building with an initial velocity of 0 m/s. After 2 seconds, its distance from the ground is 64 meters. Assuming gravity as 9.8 m/s², what is the height of the building?
सही उत्तर: क) 100m
The stone's motion can be described by equations of kinematics. Using the equation s = ut + (1/2)at² where s is displacement, u is initial velocity, a is acceleration and t is time, we get s = 0*2 + (1/2)*9.8*2*2 = 19.6 m. The height of building will be added to this distance. Therefore the total height is 64+19.6=83.6m . The option closest to this answer from the choices provided would be rounded to 80m.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The length of a simple pendulum is increased by 20%. The new time period will be: (a) Increased by 20% (b) Decreased by 20% (c) Increased by 10% (d) Decreased by 10%
सही उत्तर: ख) Decreased by 20%
The time period (T) 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 increases by 20%, the new length will be 1.2L. The new time period will then be T' = 2π√(1.2L/g) = 2π√1.2 * √(L/g) = √1.2 * (2π√(L/g)) = √1.2 * T, which is approximately a 20% increase.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A point charge +q is placed at the center of a spherical shell. The electric flux through the surface of the shell will be: (a) Zero (b) Equal to $ rac{ ext{q}}{2} rac{1}{4 imes 10^9}$ N⋅m²/s (c) Equal to $ rac{ ext{q}}{8 imes 10^9}$ N⋅m²/s (d) Infinite
सही उत्तर: क) Zero
Gauss's law states that the total electric flux through any closed surface is proportional to the enclosed charge. Since the point charge +q is at the center, it encloses no volume, and therefore the flux is zero. Option (b) incorrectly attempts to calculate the flux using a simplified formula without applying Gauss’s Law. Options (c) and (d) are incorrect as they involve calculations not based on the fundamental principles.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A monochromatic light of wavelength λ is incident on a single slit of width ‘a’. The distance between the central maximum and any secondary maximum in the diffraction pattern is 0.7λ. What is the value of ‘a’ in terms of ‘λ’? (Given, n = 1)
सही उत्तर: ग) 3λ/4
The condition for secondary maxima is given by: Δy = m * λ / a, where Δy is the distance between central maximum and a secondary maximum (m=1 in this case). We are given that Δy = 0.7λ. So, 0.7λ = m * λ / a => 0.7 = m/a. Since m=1, we have 0.7 = 1/a therefore a = 1/0.7 ≈ 1.43. Looking at the choices, 2λ/3 is the closest result as it has some proportionality to lambda.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A uniform plano-convex lens of refractive index μ and thickness d has one surface convex (R) and the other surface concave (R). A parallel beam of light is incident on the lens. Find the focal length of the lens.
सही उत्तर: घ) d(1/2 + 1/μ)
For a plano-convex lens with one surface convex (R) and the other concave, the lens maker's formula is: 1/f = (μ - 1)/(μ + 1) + R/f. When parallel light rays are incident on the lens, they get refracted through the focus. So, using the lens maker's formula for a convex surface, we have: 1/f = (μ - 1)/(μ + 1) + R/f. This simplifies to f = d(1/2+1/mu).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A uniform wire of length L and area of cross-section A is stretched to twice its original length. Assuming the stress remains constant, what will be the new strain? (Assume Young's modulus is Y)
सही उत्तर: ख) 1/4
Strain is defined as the change in length divided by the original length. When a wire is stretched to twice its original length, the new length is 2L. Therefore, the strain is (2L - L) / L = 1L / L = 1. However, the options show incorrect answers. The correct answer reflects this change in length and therefore, strain
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A gas occupies a volume of 2m³ at pressure 3 bar and temperature 300K. It expands isothermally to a volume of 6m³. What is the new pressure? (1 bar = 1000 N/m²)
सही उत्तर: ग) 9 bar
The problem involves applying Boyle's Law (P₁V₁=P₂V₂) for an isothermal process. Given P₁=3 bar, V₁=2m³, and the expansion to V₂=6m³, we solve for P₂: P₂ = (P₁V₁)/V₂ = (3 bar * 2m³)/6m³ = 1 bar. The tempting incorrect answer of '6 bar' arises because it’s an isothermal process and volume doubled, but the pressure halved to result in the final answer.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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