Physics MCQs

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The specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius. The specific heat of water is 1 calorie/gram°C = 4.186 joule/gram°C which is higher than any other common substance. As a result, water plays a very important role in temperature regulation to be used in hot water bags.

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Mica as an exception is a good conductor of heat but bad conductor of electricity.

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Archimedes’ Principle states that upward buoyant force exerted on a body immersed in a fluid is equal to the weight of the fluid displaced by the body immersed in the fluid.

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Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid or a gas below its freezing point without it becoming a solid. A good example of this phenomenon is clouds in high altitude that are an accumulation of supercooled droplets of water below their freezing point. Refrigeration using dry ice is a popular commercial application of supercooling.

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Stress is defined as resisting force per unit area of an element, on which load is applied. Stress is always perpendicular to a cross-section in the element. It is neither scalar nor is it a vector but a tensor quantity because it describes things happening in two directions simultaneously.

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Nature’s most efficient means of cooling is through the evaporation of water. Desert coolers make use of evaporative cooling that works on the principle of heat absorption by moistures evaporation. As water is evaporated, heat energy is extracted from the air to produce the cooling effect.

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Kinetic energy is the energy associated with the movement of objects. The amount of kinetic energy that an object has depends upon two variables: the mass (m) of the object and the speed (v) of the object.

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According to the Second law of Thermodynamics, heat transfer always occurs from a region/body of high temperature to another region/body of lower temperature. The process continues till the body and the surroundings reach the same temperature, at which point they are in thermal equilibrium. Transfer of thermal energy occurs mainly through conduction, convection or radiation.

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A solar cell (also called a photovoltaic cell) is an electrical device that converts the solar energy of light directly into electricity by the photovoltaic effect.

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The red colour in the sky at sunset and sunrise is due to an effect called Rayleigh scattering. At sunrise or sunset, since the Sun is low hence, at distance on the horizon, the light rays must pass through more of the atmosphere . and therefore bounce off more molecules . than at other times of day. Thus, blue light gets scattered away while red or organe manage to reach us.