Physics miscellaneous


  1. Red is used as an emergency or danger signal as









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    The effect of scattering is inversely related to the fourth power of the wavelength of a colour. Red has the highest wavelength of all the colours and is able to travel the longest distance through fog, rain, and the alike.

    Correct Option: B

    The effect of scattering is inversely related to the fourth power of the wavelength of a colour. Red has the highest wavelength of all the colours and is able to travel the longest distance through fog, rain, and the alike.


  1. Parabolic mirros are used in









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    A parabolic reflector (mirror) transforms an incoming plane wave traveling along the axis into a spherical wave converging toward the focus. Since the principles of reflection are reversible, parabolic reflectors can also be used to project energy of a source at its focus outward in a parallel beam, used in devices such as spotlights and car headlights.

    Correct Option: A

    A parabolic reflector (mirror) transforms an incoming plane wave traveling along the axis into a spherical wave converging toward the focus. Since the principles of reflection are reversible, parabolic reflectors can also be used to project energy of a source at its focus outward in a parallel beam, used in devices such as spotlights and car headlights.



  1. A pilot has to release the bomb to hit a target









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    According to Newton’s first law, an object that is at rest will stay at rest unless an unbalanced force acts upon it and an object that is in motion will not change its velocity unless an unbalanced force acts upon it. So the bomb carries the inertia of the aircraft and so has to be launched before the target so that it can hit it on time. Assuming the plane continues to fly straight forward, the plane will be directly over the target when the bomb hits.

    Correct Option: C

    According to Newton’s first law, an object that is at rest will stay at rest unless an unbalanced force acts upon it and an object that is in motion will not change its velocity unless an unbalanced force acts upon it. So the bomb carries the inertia of the aircraft and so has to be launched before the target so that it can hit it on time. Assuming the plane continues to fly straight forward, the plane will be directly over the target when the bomb hits.


  1. Stars in the sky appear to twinkle due to









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    The movement of air (sometimes called turbulence) in the atmosphere of Earth causes a series of refractions which makes the starlight to get slightly bent as it travels from the distant star through the atmosphere down to us on the ground. This means that some of the light reaches us directly and some gets bent slightly away. To our eyes, this makes the star seem to twinkle.

    Correct Option: A

    The movement of air (sometimes called turbulence) in the atmosphere of Earth causes a series of refractions which makes the starlight to get slightly bent as it travels from the distant star through the atmosphere down to us on the ground. This means that some of the light reaches us directly and some gets bent slightly away. To our eyes, this makes the star seem to twinkle.



  1. ‘Hydraulic brakes’ work on the principle of









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    Pascal’s law states that when there is an increase in pressure at any point in a confined fluid, there is an equal increase at every other point in the container. According to Pascal’s principle, in a hydraulic system a pressure exerted on a piston produces an equal increase in pressure on another piston in the system. If the second piston has an area 10 times that of the first, the force on the second piston is 10 times greater, though the pressure is the same as that on the first piston. This effect is exemplified by the hydraulic press, based on Pascal’s principle, which is used in such applications as hydraulic brakes.

    Correct Option: A

    Pascal’s law states that when there is an increase in pressure at any point in a confined fluid, there is an equal increase at every other point in the container. According to Pascal’s principle, in a hydraulic system a pressure exerted on a piston produces an equal increase in pressure on another piston in the system. If the second piston has an area 10 times that of the first, the force on the second piston is 10 times greater, though the pressure is the same as that on the first piston. This effect is exemplified by the hydraulic press, based on Pascal’s principle, which is used in such applications as hydraulic brakes.