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Mössbauer effect

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Recoilless emission and recoilless absorption of gamma photons is called Mossbauer effect. It provides us a technique for producing and studying gamma rays whose energies are extremely well defined. Mossbauer effect was discovered by Rudolf Mossbauer in 1958. This effect is applied in the experimental field by the name Mossbauer spectroscopy. Let us first understand why a  nuclear transitions  occurs. After a radioactive nucleus undergoes decay (alpha decay, beta decay, k-capture) it many times reaches to the daughter nuclei state but contains too much energy to be in a final stable state. Unlike our electrons orbiting the nucleus, the nucleus itself doesn’t really have such orbits which are easy to visualize. So, let us just imagine it having a particular quantized energy. Now, to be in a stable ground state it must lose this extra energy. It does this by emitting gamma radiation of that energy. This is the process of nuclear transition, where the nucleus transitions from one
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Lenses

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Lenses are those circular objects which looks like a cat's eye slit when viewed from the sides. We know that there are two kinds of spherical mirrors, concave mirror (which converges light at the focus) and convex mirror (which diverges light). Similarly, in case of lenses there are two major types concave and convex (other types are plano-concave, biconcave and convexo-concave and vice-versa). In case of lenses, convex lens converges light rays whereas concave lenses diverges light rays. In mirrors we polish and silver a surface so as to reflect light coming from an object but lenses require polishing of two spherical surfaces accurately so as to refract light from the object. We know that reflection means bouncing back of light from a shiny (mostly), polished surface. What is this refraction? Refraction means bending of light rays. But light travels in a straight line. What causes it to bend? The answer is change of density of medium. But it doesn't bend just anyho
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