Question

Electromagnetic radiation of 2.97 X 10 22 Hz is applied on the metal surface and caused electron emission. Determine the work function of metal If the maximum kinetic energy of emitted eletron is 1.17 x 10 -13 J .?? Please solve , thanks a lot

Answer 1

I tried this but check my maths to be sure...

Explanation:

Ok, the energy of photons of light (EM radiation)
is:
`E=hf`
Where:
`h=6.63×10^-34Js` is Planck's constant;
`f=2.97×10^22Hz` is the frequency.
Now, when this energy reaches the metal electrons are emitted with a certain velocity `v`, i.e. a kinetic energy:
`K=1/2mv^2=1.17×10^-13J`
But the electrons are bound to the metal and need some of the incoming energy (photon) to free themselves from the metal...the work Function `phi`.
So basically we have:
`"photon energy"="kinetic energy"+"work function"`
Or
`hf=K+phi`
So:
`phi=[6.63×10^-34*2.97×10^22]-1.17×10^-13=1.95×10^-11J`