(i) three photodiodes `D_(1),D_(2)` and `D_(3)` are made of semiconductors ahving band gaps of 2.5 eV 2eV and 3eV respecitvely which of them will not be able to detect light of wavelenghth 600nm
(ii) why phtoodiodes are required to operate in revese bias explain

Explanation

(i) `lambda =600`nm
energy of a photon of wavelength `lambda`
`E= (hC)/( lambda) = (6.63 xx 10^(34) xx 3xx 10^(8))/( 600 xx 10^(-9) xx 1.6 xx 10^(-19))`
The band gap energy of diode `D_(2)` (=2 eV) is less than the energy of the photon. Hence diode.
`D_(2)` will not be able to detect light of wavelegth 600 nm.
(ii) A photodiode when operated in reverse bias carrier dominated reverse biase current with greater case than when forward biased.