What is the largest wavelength for emission of electrons from a photosurface?

[prakriti]

1) when light of wavelength 2.08*10^-7m falls on a photosurface, a voltage of 1.40V is required to stop the emitted electrons from reaching the anode. What is the largest wavelength of light that will result in emission of electrons from this photosurface?


2) To determine the work function of given photosurface, light of wavelength 2.3*10^-7 m is directed at the surface and the stopping voltage is recorded. When light of wavelength 1.8*10^-7m large as the previous one. Find the work function.

 

[armis]

What is the relationship between the wavelength of the incident light and the energy of the emitted electrons?

 

[prakriti]

isnt it f = speed / wavelength
and Energy = h*f
so Energy = h*speed/wavelength
but i just can't figure out the problem.. please help!

 

[armis]

look up the photoelectric effect