It takes 6.08 multiplied by 10-19 J of energy to remove one electron from a certain metal surface What is the maximum wavelength of light capable of causing this effect?

Answer 1

best way to write above question is:

Work function = 6.08*10^-19J This is energy Min required to free one electron.

what max wavelength is requred to cause this event?

remember wavlength inversely proportional to energy of photon via planks constant h

hence E = hV but E = hc / (wavelength)

where

E = energy photon

V = frequency of photon

h = planks constant = 6.626068 × 10-34 m2 kg / s

now, because Min energy is proportional to max wavelength, which is related to frequency:

V = E/h = (6.08*10^-19J) / ( 6.626068 × 10-34 m2 kg / s)

= 9.176 * 10^14hz

now C = V*(wavelength)

so (wavelength) = (3*10^8m/s) / (9.176*10^14hz) =

= 3.27*10^-7 meters

between 0.7 and 300 micrometres is infra-red, but this is 0.327 micrometers!! This seems like a very large wavelength, and therefore low energy value.