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Author Archives: admin

Does a photon have a de Broglie wavelength?

Yes a photon has de Broglie wavelength.In 1924,Louis de Broglie proposed that a particle must also act like wave,in silmilar way,wave behave like particles. In de Broglie hypothesis an electromagnetic wave is the de-Broglie wave for a photon moving with speed c.According to de-Broglie ,the wavelength of the photon is given by the relation: λ = h/p Where P is ...

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What are X-rays?

What are X rays made of: X-rays are the electromagnetic waves which are emitted by the atoms of those metals which have large atomic number,large number of protons in their nuclei so that the pull of the nuclei on their electrons is very large.When an electron of K or L shell of such an atom is displaced from these shells ...

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What is difference between free and forced oscillations

Free Oscillations: A body is said to be executing free vibrations when it oscillates without the interference of an external force.For example,when simple pendulum is slightly displaced from its mean position vibrates freely with its natural frequency that depends only upon length of pendulum. Forced Oscillations: If an oscillating system is subjected to an external periodic force,then forced vibrations will ...

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Acceleration due to gravity formula and problems

What is gravitational acceleration? Acceleration of a freely falling bodies is called gravitational acceleration.The value of gravitational acceleration is 10 ms-².   Why value of g varies with altitude? Above formula shows that the value of acceleration due to gravity g depends on the radius of the earth at its surface.The value of g is inversely  proportional to the square ...

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What is the law of conservation of enegy

What does law of conservation of energy mean? According to law of conservation of energy:”Energy can neither be created nor is it destroyed.It can only be transformed from one form to another.A loss in one form of energy is accompanied by an equal increase in the other forms of energy.The total energy remains constant.” According to Einstein’s mass energy relation: ...

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alpha beta and gamma radiation

Discovery of Radioactivity: In the March 1896 Henri Becquerel announced the discovery of radioactivity similar to X-rays.Although rays (X-rays) had been discovered less than four month earlier it was already known that X-rays come from the fluorescence wall of the discharge tube and thus it was thought that fluorescence and phosphorescence might be responsible for them. Becquerel known that Uranium ...

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What is thermal radiation

Thermal radiation: Radiation emitted by such a body due to its temperature is called thermal radiation.All bodies not only emit such radiation but also absorb it from their surroundings.If the rate of absorption and emission from a body become equal ,the body is said to be in thermal equilibrium with its surroundings. The spectrum of thermal radiation from a hot ...

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Can a transformer operate on DC?

A transformer cannot operate on a steady or unchanging dc voltage such as that of a battery.It requires a voltage which rises and falls.Since an ac voltage not only changes its magnitude but its direction as well,it is used to operate the transformers. However,a transformer will operate from dc voltage if this voltage also undergoes changes.Transformers used for audio amplifiers ...

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What is Photovoltaic effect

Photovoltaic effect: An effect arising when a junction exists between two dissimilar materials and one of the materials is exposed to electromagnetic radiation,usually in the range near ultraviolet to infrared.The two materials may,for example,be a metal and a semiconductor or two semiconductors of opposite polarity,the combination forming a Schottky barrier and a P-N junction respectively.A forward voltage appears across the ...

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What instrument is used to measure atmospheric pressure?

Barometer is an instrument used to measure atmospheric pressure. How can we measure atmospheric pressure by mercury barometer? Mercury barometers consist of a glass tube about 80 cm long,closed at one end.The tube is filled with mercury and then placed,open end downward,in a reservoir of mercury.As the atmospheric pressure changes ,the level of the mercury changes and to a lesser ...

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