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Question: The maximum wavelength of electromagnetic radiation which can create a hole electron pair in germani...

The maximum wavelength of electromagnetic radiation which can create a hole electron pair in germanium (Given that forbidden energy gap in germanium is 0.72eV0.72eV)

A

1.7×106m1.7 \times 10^{- 6}m

B

1.5×105m1.5 \times 10^{- 5}m

C

1.3×104m1.3 \times 10^{- 4}m

D

1.9×105m1.9 \times 10^{- 5}m

Answer

1.7×106m1.7 \times 10^{- 6}m

Explanation

Solution

: here, Eg=0.72eV=0.72×1.6×1019jE_{g} = 0.72eV = 0.72 \times 1.6 \times 10^{- 19}j

If λ\lambdais the maximum wavelength of electromagnetic radiation which can create a hole- electron pair in germanium, then

Eg=hcλE_{g} = \frac{hc}{\lambda}

Or λ=hcEg=6.62×1034×3×1080.72×1.6×1019=1.7×106m\lambda = \frac{hc}{E_{g}} = \frac{6.62 \times 10^{- 34} \times 3 \times 10^{8}}{0.72 \times 1.6 \times 10^{- 19}} = 1.7 \times 10^{- 6}m