Physics MCQs

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Surface tension is the tendency of liquid surfaces to shrink into the minimum surface area possible. Surface tension allows insects, usually denser than water, to float and slide on a water surface. It is the reason for the water droplet’s round shape.

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The velocity of an object undergoing uniform circular motion is always changing (because the direction is always changing). Further, since the acceleration is centripetal, it must always point toward the center of the circle; so, as the object moves around the circle, the acceleration vector is also constantly changing direction. Notice that for an object in uniform circular motion, both the velocity and the acceleration are changing because the directions of these vectors are always changing, even though their magnitudes stay the same. In this question, only speed remains unchanged.

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Pure silicon has a negative coefficient of thermal expansion for temperatures and hence it shows contraction effect.

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A CD or DVD has closely spaced tracks which work as a diffraction grating to form the familiar rainbow pattern seen when looking at a disk.

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C.V Raman discovered the Inelastic scattering of light by molecules in 1928, also named as ‘Raman effect’ Raman scattering is the inelastic scattering of a photon by molecules which are excited to higher vibrational or rotational energy levels. He was the first Indian Physicist to win the Nobel Prize for Physics in 1930. C.V Raman has also been bestowed with the Bharat Ratna Award.

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J.J Thompson was the first scientist to discover and identify the electrons and to make the discovery of the first subatomic particle. He was also the first scientist to find evidence for isotopes of a stable (non-radioactive) element in 1913, as part of his exploration into the composition of canal rays (positive ions). His experiments to determine the nature of positively charged particles led to the development of the mass spectrograph. J.J Thompson belonged to United Kingdom. He won the Nobel Prize in Physics in 1906 for his work on the conduction of electricity in gases.

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The motion of an object under free fall is a case of uniform acceleration. If an object is released from a height near the surface of earth, it accelerates downwards under the influence of a gravity pull with acceleration due to gravity.

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A projectile will achieve maximum horizontal range when it is projected at an angle of 45°. This concept of maximum horizontal range is used by athletes in long jump, javelin throw, cricket ball throw etc

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The force acting on a body for a short time are called as Impulse. Example: hitting a ball with a bat. Impulse = average force x time It is a measure of total effect of the force. Its unit is Ns

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Kinetic energy of a body is half the product of mass of the body and square of the velocity of the body. K.E = 1/2(mv²) Kinetic energy depends on the frame of reference. Kinetic energy of a body is always positive.