Q158 / 160 · TS EAMCET 2021 (04 Aug Shift 2) · Physics

In a p-n junction, an electric field of 5×105 V m exists in the depletion region. The minimum kinetic energy of a conduction electron, in order to diffuse from n-side to the p-side, is found to be 3.2×10-20 J. The width of the depletion region is,

  • A
    2×10-4 cm
  • B
    8×10-5 cm
  • C
    5×10-6 cm
  • Correct answer
    D
    4×10-5 cm

Solution

The kinetic energy in terms of electric potential, K.E.=eV, it means the value of electric potential, V=K.E.e=3.2×10-201.6×10-19, now the relation between electric field strength and electric potential in terms of the width of the depletion region, 
d=VE=3.2×10-201.6×10-195×105=4×10-5 cm. 

Hence, the correct answer is option: 'D'.

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