Question 3
If the velocity of sound in a solid is of the order 103 m/s, compare the frequency of the sound wave λ = 20 Å for (a) a monoatomic system and (b) acoustic waves and optical waves in a diatomic system containing two identical atoms (M=m) per unit cell of interatomic spacing 2.2 Å.(10)
Question 4
4.1. The conductivity of silver is 6.5 x 107per Ohm per m and number of conduction electrons per m3 is 6 x 1028. Find the mobility of conduction electrons and the drift velocity in an electric field of 1 V/m. Given m = 9.1 x 10–31 kg and e = 1.602 x 10–19 C.(5)
4.2 What is Lorentz number? The thermal and electrical conductivities of Cu at 200C are 390 Wm-1K-1 and 5.87 x107W-1m-1 respectively. Calculate Lorentz number. (5)
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