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Electronic Devices and Circuits - Engineering

Q1:

In case of photo conductor for germanium when forbidden energy gap is 0.72 eV, the critical wavelength for intrinsic excitation will be

A 1.43 m

B 1.43 mm

C 1.73 mm

D 1.73 x 1012 m

ANS:C - 1.73 mm

E = hc/lamda.
Lambda = hc/E.
= 6.625 * 10^-34 * 3 * 10^8/0.72 * 1.62 * 10^-19.
= 1.73 micro meter.