Physics miscellaneous

Physics miscellaneous

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Physics miscellaneous
  1. The mass of a body measured by a physical balance in a lift at rest is found to be m. If the lift is going up with an acceleration a, its mass will be measured as








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    Mass is the quantity of matter possessed by a body. It will be the same even if the lift goes up with acceleration.

    Correct Option: C

    Mass is the quantity of matter possessed by a body. It will be the same even if the lift goes up with acceleration.

  1. When two semiconductors of pand n-type are brought in contact, they form p-n junction which acts like a/an








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    P-n junction is a device which flows current in one direction when it is forward biased and when it is reverse biased it doesn’t flow any current through it. So it acts as an rectifier device to convert sinusoidal current to uni-direction. A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction.

    Correct Option: C

    P-n junction is a device which flows current in one direction when it is forward biased and when it is reverse biased it doesn’t flow any current through it. So it acts as an rectifier device to convert sinusoidal current to uni-direction. A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction.

  1. When a body is immersed in a liquid, the force acting on it is








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    According to the Principle of Flotation, when a body is immersed in a fluid, two forces act on it: (1) The weight of the body acting vertically downward through the centre of gravity of the body, and (2) The upthrust of the fluid acting vertically upward through the centre of gravity of the fluid displaced, i.e., centre of buoyancy. The upthrust is also termed as buoyant force.

    Correct Option: D

    According to the Principle of Flotation, when a body is immersed in a fluid, two forces act on it: (1) The weight of the body acting vertically downward through the centre of gravity of the body, and (2) The upthrust of the fluid acting vertically upward through the centre of gravity of the fluid displaced, i.e., centre of buoyancy. The upthrust is also termed as buoyant force.

  1. A white and smooth surface is








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    Shiny surfaces are poor absorbers of heat radiation and the best reflectors of heat radiation. Black surfaces are the best emitters and best absorber of heat radiation.

    Correct Option: D

    Shiny surfaces are poor absorbers of heat radiation and the best reflectors of heat radiation. Black surfaces are the best emitters and best absorber of heat radiation.

  1. In a filament type light bulb most of the electric power consumed appears as








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    When electricity is passed through the filament, the filament gets hot. Depending on the temperature of the filament, radiation is emitted from the filament. The filament’s temperature is very high, generally over 2,000°C. At this high temperature of 2,000°C, about 5 percent of the electrical energy converts into visible light and rest of it is emitted as heat or infrared radiation.

    Correct Option: B

    When electricity is passed through the filament, the filament gets hot. Depending on the temperature of the filament, radiation is emitted from the filament. The filament’s temperature is very high, generally over 2,000°C. At this high temperature of 2,000°C, about 5 percent of the electrical energy converts into visible light and rest of it is emitted as heat or infrared radiation.