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ELECTRIC POTENTIAL

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  Electric potential :-         C url of electrical field is zero therefore, electric field is conservative field. Scalar potential is defined only for conservative field.        In the following we first show that curl of electric field is zero . We know field of a point charge at the origin.      If we take the integral along a closed path Then, . Apply Stoke theorm   Here,  This result can be generalised for any charge distribution using the principal of superposition. The general result is 
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Properties of reciprocal lattice

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  RECIPROCAL LATTICE:-   M any properties of crystalline substance are different in different directions. W.H.Miller explain the concept of miller indices to represent the planes and directions of a crystal. In real practice there are many set of planes with different orientations and spacings and it becomes difficult to visualise the slope of the planes. Since all parallel planes have a common normal and simillar indices , so the miller indices of a plane can not be uniquely defined. Therefore to understand many crystallographic problem we consider the normal to be set of planes rather than the planes themselves. The orientation of plane is understood by the direction of normal. DEFINITION OF RECIPROCAL LATTICE:-       T he reciprocal lattice in Fourier space is an infinite periodic three dimensional array of points whose spacings are inversely proportional to the distance between planes in the direct lattice.     The need for devising the concept of ...
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RADIOACTIVITY

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Radioactivity: The uranium salt emitted the rays spontaneously.The phenomenon of spontaneous emission of radiations by heavy elements is called Radioactivity . Properties of nuclear radiation: 1. Properties of Alpha(α) rays: - Alpha(α) particles is a helium nucleus consisting of two protons and two neutrons. - The velocity of α- particles ranges from 1.4 x 10^7 m/s to 2.05 x 10^7 m/s. -They are deflected by electric and magnetic fields. - Alpha (α) particles produce fluorescence in substance like zinc sulphide and barium platinocyanide. - They are massive particles and hence easily stopped by an aluminium sheet of only 0.02mm thick or even by ordinary sheet of paper. - They have great ionising power. Each α-particles produces thousands of ions pairs in a gas before being absorbed. - They get scattered while passing through this metal foils. - They affect a photographic plate. - They can produce artificial radioactivity in certain elements and can produce nuclea...
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