A photon of wavelength 350nm and intensity 1.00W/m2 is directed at a Potassium surface (Work Function = 2.2 eV).
Will photoelectrons be emitted from the surface?

Question

A photon of wavelength 350nm and intensity 1.00W/m2 is directed at a Potassium surface (Work Function = 2.2 eV).
Will photoelectrons be emitted from the surface?

anonymous · Answer

Need to find energy of photon from wavelength. 
E = h f 
c = f lambda 

f= frequency, lambda = wavelength, c is speed of light.
Once you have energy, see if it exceeds work function, so that electron is emitted.

anonymous · Answer

6.63 × 10^-34 × (3 × 10^8 ÷ (350 × 10^-9)) - (2.2 × (1.6 × 10^-19)) =
2.1628571e-19	

So there will be photoelectric effect?

lastdaywork · Answer

@Thame 
If hf >= work function; then (and only then) electrons will be emitted

anonymous · Answer

Ok thanks.

lastdaywork · Answer

Although, be careful with the units (like here work function is in eV)

anonymous · Answer

Yes so Ive converted the ev to joules by multiplying 2.2 by 1.6x10^-19

lastdaywork · Answer

It was hard to understand your calculations, so I advised you anyway :)