Question

Q1.Electrons are accelerated by 344 V are reflected from a crystal . The first order max. occurs when glancing angle is 30 . Determine the spacing of the crystal .​​


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Answer 1

Explanation:

For constructive interference, 2dcosi=nλ and also wavelength, λ=2meVh

So, 2dcosi=n×2meVh

Squaring both sides, 4d2cos2i=2meVn2h2

V=8d2mecos2in2h2=8(1×10−10)2(9.1×10−31)(1.6×10−19)(cos230)(1)2(6.6×10−34)2=49.8V∼50V  (we assume first order interference and take n=1)