## post module assessment Q35B

Jane Burgan 1C
Posts: 73
Joined: Fri Sep 28, 2018 12:15 am

### post module assessment Q35B

Molybdenum metal must absorb radiation with a minimum frequency of 1.09 x 10^15 s-1 before it can emit an electron from its surface.
If molybdenum is irradiated with 194 nm light, what is the maximum possible kinetic energy of the emitted electrons?

I'm pretty sure we have to solve the problem using the Ek = hv - work function equation (but not entirely haha), but to find the frequency of the photon do we use the c=wavelength*frequency equation? If so, do we convert the 194 nm to meters?

gwynlu1L
Posts: 62
Joined: Fri Sep 28, 2018 12:19 am

### Re: post module assessment Q35B

You know what the work function for the given problem is, since they give you the lowest possible frequency. So, hv= work function. First, use 1.09 x 10^15 Hz to calculate the energy of the work function using E = hv. Then, use the wavelength they give you to calculate the frequency of the given light using c = lambda x v, and then use that frequency to solve for the energy of the photon. Now, you should have 2 values to solve for the kinetic energy (you have energy of the photon and the work function, so find the difference).

Jordan Lo 2A
Posts: 85
Joined: Fri Sep 28, 2018 12:25 am

### Re: post module assessment Q35B

I used the equation E=hv and v=c/lambda to find energy of the photon, but my answer for energy is 1.02*10^34 J. Is this correct? It seems like it's too small of a number but I can't find my mistake