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Modern Physics

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 ...

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bohr atomic model and theory for hydrogen atom with postulates

 Bohr’s theory of the  hydrogen atom The Rutherford model of atom and the experimental formula of atomic spectra helped Bohr is solving the problem of atomic structure.In 1913 he proposed a model for the structure of a hydrogen atom based on his experimental observations.  Bohr atomic model postulates Neil Bohr based his theory of hydrogen atom on the following three ...

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Heisenberg uncertainty principle: Statement,formula & equation

 Heisenberg  uncertainty principle Statement Uncertainty principle is defined as:”It is impossible to measure simultaneously both the position and momentum of a microscopic particle with accuracy or certainty.” When we are studying a large moving object say a planet,then we can follow its definition path on which it travels.If we know its initial position and momentum,then we can predict its position and ...

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Black body radiation and planck’s radiation law

Black body radiation basics When a body is heated,it emits radiation.The nature of the radiation depends upon the temperature.At low temperature,a body emits radiation which is principally of long wavelengths in the invisible infrared region.At high temperature ,the proportion of shorter wavelength radiation increases. Furthermore,the amount of emitted radiation is different for different wavelengths.It is of interest to see how ...

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What is laser? how does it works?

What is laser? The name “LASER” stands for light Amplification by Stimulated Emission of Radiation.The lasers are used to produce light having following properties: Monochromatic Directionality Brightness Coherence Polarization One of the most important property of laser light is its monochromaticity. The word monochromatic comes from Greek word monos means single and chroma means colour. actually all lasers have very ...

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Photoelectric effect:Definition,equation,applications and problems

What is photoelectric effect? “When light of suitable frequency falls on a metal surface, electrons are emitted from the metal surface.This phenomenon is called photoelectric effect.” The electron emitted in this process are known as photoelectric. Explanation Experimental Setup for photoelectric effect The apparatus used to observe the photoelectric effect is shown in above Figure: It consists of an evacuated ...

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