Physics MCQs

Notes:
Water at ordinary temperatures contracts and increases in density as it is cooled, like most substances. But at 4°C, it reaches its maximum density and then decreases in density as it approaches the freezing point. This is referred to as anomalous property of water according to which density reduced with the decreasing temperature.

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A parsec is a unit of length used to measure large distances between objects outside our Solar System. One parsec is the distance equal to about 3.26 lightyears in length.

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Frequency is the number of occurrences of a repeating event per unit of time. It is also referred to as temporal frequency, which emphasizes the contrast to spatial frequency and angular frequency. The period is the duration of time of one cycle in a repeating event, so the period is the reciprocal of the frequency. Its SI unit is Hertz.

Notes:
Pitch is a perceptual property that allows the ordering of sounds on a frequency-related scale. Pitch may be quantified as a frequency, but pitch is not a purely objective physical property; it is a subjective psycho-acoustical attribute of sound. When the frequency is high, the wavelength of the sound is shorter.

Notes:
Real gases approximate ideal gases when their pressure is relatively low, and their temperature is reasonably high. A real gas deviates increasingly from ideality as it is compressed and cooled to near the point at which it will condense into a liquid. Compressing forces the molecules closer together so that intermolecular forces become stronger, and cooling reduces the kinetic energy of the molecules, so that they are more easily held by these forces.

Notes:
Perceived loudness of sound is a psycho-acoustic quantity that depends on sound pressure level, the frequency spectrum, and the time behavior of the sound. The sone is a unit of perceived loudness that was proposed by Stanley Smith Stevens in 1936.Being a unit of how loud a sound is perceived, the sone scale of loudness is based on data obtained from subjects who were asked to judge the loudness of pure tones and noise. One sone is arbitrarily set equal to the loudness of a 1,000-hertz tone at a sound level of 40 decibels.

Notes:
The human ear cannot distinguish echo from the original direct sound if the delay is less than 1/15 of a second. The velocity of sound in dry air is approximately 343 m/s at a temperature of 25°C. Therefore, the reflecting object must be more than 17.2m from the sound source for echo to be perceived by a person located at the source.

Notes:
The energy possessed by a body owing to its position or configuration is called potential energy. The wound watch has potential energy on account of its wound state. As the spring unwinds, it does work to move the hands of the watch. Thus, a wound spring has the potentiality to do work.

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When a ray of light falls on seashell, its small amount gets refracted (slightly polarized) and rest almost gets reflected back (fully polarized). So it gets a golden view because of polarization.

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Radioactive elements can be traced out in living cell through a technique called Autoradiography. The technique detects the radiation emitted by radioactive particles present in a cell or tissue.