LAWS OF TRANSVERSE VIBRATIONS

BRAVIAS CRYSTALS -7 CRYSTAL SYSTEMS

Bravias crystals : There are 7 different basic crystal lattices according to the dimensions (a,b,c) and their angles( ⍺ , 𝛽, ℽ ) of unit cell which are called Bravias crystals. 1 Cubic crystal system : a=b=c and α=β=γ=90 example : NaCl available systems are simple cubic, face centered and body centered cubic systems 2 Tetragonal a=b ≠ c and α=β=γ=90 example SiSO4 available systems : simple and body centered cubic systems. 3 Orthorhombic a ≠ b ≠c and α=β=γ=90 example: BaSO4 available systems are simple, body centered ,face centered and base centered cubic systems. . 4 Monoclinic (rhombohedral ) a ≠ b ≠c and α=β=90γ=120 example: Na2So4...

RUBY LASER - CONSTRUCTION AND WORKING

Ruby laser Ruby laser is a solid state laser. Ruby is a transparent crystal of aluminium oxide and its chemical composition is Al 2 O 3 . An amount of aluminium atoms are replaced by chromium atoms with 0.5%. Then the crystal (Al 2 O 3 , Cr2O3) will attain a light pink colour. Construction : A ruby rod of length 4 cm and diameter 0.5 cm to 1 cm is used . The end faces of the rod are grounded and polished to be parallel to each other. One face of the rod is silvered and it acts s perfect reflector. The other face is semi silvered. The ruby rod is surrounded by an optical flash helical pipe filled with Xenon gas. The two ends of Xenon pipe are connected to a high tension voltage for pumping the chromium ions to excited state. The whole arrangement is enclosed in an evacuated chamber. Working : Ruby laser works on 4 level pumping principle. when the high tension is applied the xenon pipe relea...

BRAGG'S LAW - DIFFRACTION OF X-RAYS THOUGH CRYSTAL ALTTICE

Diffraction of X-rays through crystal lattice: (Bragg’s law) X-rays are used to identify the structure of a crystal. The property of diffraction of x-rays are used in this procedure. The wave length of ordinary light is very large comparing with the value of inter planar spacing. Hence ordinary light cannot penetrate trough the lattice planes. But X-rays penetrate through the lattice planes and they are scattered by the atoms of the crystal lattice. Each atom acts as an opaque and the distance between two atoms acts as narrow slit. Hence the crystal lattice is considered as diffraction grating. When x-rays are scattered by the successive parallel planes they diffract with each other and produce diffraction pattern.by studying the diffraction pattern we can find different sets of planes located in the lattice at different directions. Bragg used X-rays to study the structure of crystals. He derived the co...

PHYSICS

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