What is the max kinetic energy of photoelectrons from monochromatic beam?

[utkarshakash]

Homework Statement

The electric field associated with a monochromatic beam becomes zero 1.2*10^15 times per second. Find the max kinetic energy of the photoelectrons when this light falls on a metal surface whose work function is 2.0 eV.

Homework Equations

The Attempt at a Solution

K(max)=hv-W where W=work function.
I have to find frequency from the given information which I don't know. But I guess it should be 1.2*10^15. Not sure about that.

 

[STEMucator]

Homework Statement

The electric field associated with a monochromatic beam becomes zero 1.2*10^15 times per second. Find the max kinetic energy of the photoelectrons when this light falls on a metal surface whose work function is 2.0 eV.

Homework Equations

The Attempt at a Solution

K(max)=hv-W where W=work function.
I have to find frequency from the given information which I don't know. But I guess it should be 1.2*10^15. Not sure about that.

I believe your interpretation that $f = 1.2 \times 10^{15} Hz$ would be the case.

Convert your work function into Joules before you use it.

Your equation also seems to be a bit off, it should read:

$E_k = hf - W$

 

[nasu]

Think about a sine function (or even better draw it).
How many times does it go through zero in a period?
It is easier to see if you take a period from a maximum to the next maximum in the sine wave.

 

[utkarshakash]

Think about a sine function (or even better draw it).
How many times does it go through zero in a period?
It is easier to see if you take a period from a maximum to the next maximum in the sine wave.

I got that. Thanks!

 

[nasu]

Then what is the frequency of the light, in the problem?
Or you solved the question already?

 

[utkarshakash]

Then what is the frequency of the light, in the problem?
Or you solved the question already?

I solved that.