Physics MCQs

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Friction is the main reason for any object to come to rest. It is the main reason for the stability of the objects on earth.

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The force of attraction acting between the molecules of same material is known as cohesive force. Cohesive force is the action or property of like molecules sticking together, being mutually attractive.

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When a barometer is taken down into a coal mine, the mercury level rises. This is because the temperature increases as you move down the Earth’s crust. There is also very little wind, so the warmth can’t distribute the temperature and moderate it.  A barometer is an instrument that measures pressure. In a coal mine, the pressure is higher than normal pressure. When a barometer is taken down into a coal mine, it shows a greater reading.

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Atmospheric pressure is the force that causes liquid to rise in a syringe when the piston is pulled up. When the syringe is placed with its opening in a liquid and the plunger is pulled up, the air pressure inside the barrel becomes much less than the atmospheric pressure acting on the liquid. Fluids flow from a high pressure area to a low pressure area. Once the pressure inside the syringe is lower than the pressure outside the syringe, the fluid will flow into the syringe.

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Ultrasound corresponds to sound waves with frequencies exceeding the upper limit of human perceptible sound, generally above 20 kHz. Humans, typically, can perceive sounds ranging between 20 Hz and 20 kHz. Ultrasound, therefore, is beyond the auditory range of humans and is employed in technologies like medical imaging and sonar devices due to its unique properties.

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Steradian is the unit of Solid Angle (Angle in Space). One steradian is defined as the solid angle of a sphere subtended at the centre of a sphere by that surface of the surface whose area is equal to the square of the sphere’s radius. Its symbol is sr.

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The unit of Coefficient of Mutual inductance is henry lambert is the S.I unit of Luminance weber is the S.I unit of Magnetic Flux candela is the S.I unit of Luminous Intensity

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When an object moves with constant negative acceleration, having positive initial velocity, the velocity-time graph is a straight line having slope more than 90°. When an object moves with constant positive acceleration, having positive initial velocity, the velocity-time graph is a straight line having slope less than 90°.

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The angular acceleration of a body moving with constant angular velocity is 0. Angular acceleration of an object in circular motion is defined as the time rate of change of its angular velocity.

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A unit vector is unit less and dimensionless. A vector cannot be divided by a vector as a vector cannot be divided by a direction. A vector does not change, when it is displaced to itself. Time, Pressure, Surface Tension, Current are some of the quantities that have direction but are not vectors. A physical quantity is a vector only when it follows commutative law of addition of vectors.