Conductivity of a photodiode starts changing only if the wavelength of incident light is less than 660 nm. The band gap of photodiode is found to be (X/8) eV The value of X is : (Given, h = 6.6 x 10⁻³⁴ Js, e = 1.6 x 10⁻¹⁹C)
(1) 15
(2) 11
(3) 13
(4) 21
