General Science - Physics

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Optical Fibre technology works on the principle of Total internal reflection of Light. It helps in transmitting light signals from one place to another with a negligible loss of energy, thereby enabling to carry more signals than copper cables.

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The following laws are dealt with in the classical physics: 1. Law of conservation of energy 2. Law of conservation of angular momentum 3. Law of conservation of linear momentum 4. Law of conservation of charge

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Electron microscope works on the principle of Wave Nature of electrons. Electron microscopes use an electron beam instead of visible light and an electron detector instead of our eyes. An electron beam allows us to see at very small scales because electrons can also behave as light due to its wave nature.

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X-rays were discovered by Wilhelm Conrad Roentgen. W.C Roengten discovered X-Rays while actually working on Cathode rays. X-rays is a form of electromagnetic radiation having a wavelength ranging from 0.01 to 10 nanometers and frequencies in the range 30 petahertz to 30 exahertz. Some Uses of X-Rays: The main use of X-rays is in medicine to check for a broken bone inside body. X-rays can also be used to kill cancer cells. X-rays are used at security checks at airports, railway stations etc. to check customers and baggage. X-rays are also used art historians to see if a picture has been painted on top of an older one. X-ray diffraction is also very important in spectroscopy and as a basis for X-ray crystallography.

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Law of Conservation of Angular Momentum: if the total external torque acting on a system is zero, the angular momentum of a system remains constant. Angular Momentum is the momentum associated with the rotation of an object. Angular Momentum = moment of Inertia X angular Speed

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Edwin Hubble, an american astronomer, and was the first to prove that the universe is expanding. According to Expanding Universe theory, the universe is presently expanding. Hubble proved that there is a direct relationship between the speeds of distant galaxies and their distances from Earth. This is now known as Hubble’s Law.

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Out of the given options, fermi is the smallest unit for measurement of distance. 1 micron = 10^-6 m 1 nanometre = 10^-9 m 1 angstrom = 10^{-10m 1 fermi = 10-15m The above four units are used for the measurement of small distances.}

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The unit of impulse is Ns. Impulse = Force(N) x Time(s) Impulse can be defined as the integral of a force, F, over the time interval, t, for which it acts.

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The unit of Inductive Reactance is ‘ohm’. Inductive Reactance = Angular frequency x Inductance Inductive reactance is defined as the opposition to a changing current flow. It is measured in ohm. Any changing current in an inductor will be impeded because of the inductance associated with it.

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The S.I. unit for Luminous Intensity is candela. The symbol used for candela is cd. Mole is the S.I unit for Quantity of Matter ampere is the S.I unit for Electric Current. Weber is the S.I unit for Magnetic Flux Luminous Intensity is the amount of light that a point source radiates in a given direction