Study HubHubPage 96/118Scan verified MCQs with the answer highlighted, then open explanations when you want the reasoning.
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Speed Of Light Measurement
The velocity of light was determined accurately by____________________?
Albert A. Michelson is credited with the most accurate early measurements of the speed of light using precise interferometry techniques, making option B correct.
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Classical Mechanics
The relation between the escape velocity (V_esc) and orbital speed (V_o) is given by____________________?
The escape velocity (V_esc) is related to the orbital velocity (V_o) by the formula V_esc = √2 × V_o, which is approximately 1.414 times V_o. This means the escape velocity is about 1.414 times the orbital speed at the same distance from the central body. Among the given options, the closest correct relation is V_esc = 2 V_o, which is option D. Although the exact factor is √2 (approximately 1.414), option D is the best available choice in the given options.
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Tides
The tides raise the water in the sea roughly how many times in a day?
Tides typically cause the sea level to rise and fall about twice each day due to the gravitational pull of the moon and the sun, resulting in two high tides and two low tides approximately every 24 hours.
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Classical Mechanics
The escape velocity from the Earth's surface in km/s is____________________?
The escape velocity from the Earth's surface is approximately 11.2 km/s. Among the given options, 9.5 km/s (option C) is the closest to the true value. The originally marked answer 'B' (7.5 km/s) is incorrect. The escape velocity is calculated by the formula v = sqrt(2GM/r), and for Earth, it is about 11.2 km/s.
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Wave Optics
In the shadow of a ball, the central portion appears bright. This happens due to____________________?
The bright central portion in the shadow of a ball is due to diffraction, where waves bend around the edges and interfere constructively at the center, creating a bright spot known as the Poisson or Arago spot.
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Motion
When the speed of a moving body is doubled, then____________________?
Momentum is directly proportional to velocity, so doubling the speed doubles the momentum. Kinetic energy depends on the square of the speed, so it actually quadruples, not doubles. Potential energy depends on height, not speed, and acceleration is unrelated to speed in this context.
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Electricity and Magnetism
The electrons in the conduction band are free to____________________?
Electrons in the conduction band are free to move and thus can transport electric charge, which is the fundamental principle behind electrical conductivity in materials.
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Elasticity
A uniform steel wire of length 4 m and cross-sectional area 3×10⁻⁶ m² is extended by 1 mm by the application of a force. If the Young's modulus of steel is 2×10¹¹ N/m², what is the energy stored in the wire?
The energy stored in the wire is given by (1/2) × stress × strain × volume. Using Young's modulus (Y = stress/strain), the energy stored can be calculated as (1/2) × Y × (strain)^2 × volume. Substituting the given values yields approximately 0.025 J, which corresponds to option A.
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Wave Properties
Which experiment shows that the wavelength of light is smaller than that of sound?
The diffraction experiment demonstrates that light waves have much smaller wavelengths than sound waves because light diffracts less noticeably than sound under similar conditions. This difference in diffraction patterns indicates the smaller wavelength of light compared to sound.
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Work And Energy
Work done by the force of friction is____________________?
The work done by the force of friction is always negative because friction opposes the direction of motion, removing energy from the system.