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Esplain the Rotating Crystal
Rotating Crystal Method of the x-ray
spectrometen with diagram (3+1 m)
Answers
Answer:
Bragg's spectrometer method is used for studying crystals using X-rays.
The apparatus consists of a X-ray tube from which a narrow beam of X-rays is allowed to fall on the crystal mounted on a rotating table. The rotating table is provided with scale and vernier from which the angle of incidence θ can be measured.
An arm which is rotating about the same axis as the crystal table, carries an ionization chamber. The rays reflected from crystal enter into the ionization chamber and ionize the gas present inside. Due to the ionization, current produced is measured by electrometer. The current of ionization is a direct measure of intensity of reflected beam from the crystal. For different angles of incidence, the corresponding ionization current is measured from the electrometer. These values are plotted in the form of graph.
For sodium chloride, the maximum reflection for peaks for 100 plane occurred at θ=5.9
0
,11.85
0
and 18.15
0
. The sines of these angles are 0.103,0.205 and 0.312 which are in the ratio 1:2:3. These peaks represent the first, second and third order reflection. The ratio confirms the correctness of Bragg's equation.