The threshold energy for photoelectric emission of electrons from a metal is 3.056 xx 10^(-15) joule. If light of 4000 Å wavelength is used, will the electrons be efected or not ? (h = 6.63 xx 10^(-34) Joule sec)

The threshold energy for photoelectric emission of electrons from a me

1.	The threshold energy for photoelectric emission of electrons from a metal is 3.056 xx 10^(-15) joule. If light of 4000 Å wavelength is used, will the electrons be efected or not ? (h = 6.63 xx 10^(-34) Joule sec)
Answer» Solution :ELECTRONS will be ejected only if the ENERGY of incident LIGHT is greater than the threshold energy. Energy of the incident light `= hv = h (C)/(lamda) = (6.63 xx 10^(-34) xx 3 xx 10^(8))/(4000 xx 10^(-10)) J = 4.97 xx 10^(-19) J` Thus is less than threshold energy