Photoelectric Cells: What Are They and Why Evacuated?

[bael]

I was wondering why photoelectric cells are evacuated

 

[Borek]

Think how they work.

 

[bael]

Think how they work.

light of a certain frequency hits a metal and frees some electrons, which then travel toward the positive cathode.

 

[Borek]

So far so good. Now think about the "travel towards the cathode part".

 

[bael]

So far so good. Now think about the "travel towards the cathode part".

is it because the electrons could possibly collide with the oxygen and other electronegative gases, ionizing them and thus giving a smaller reading on the current meter?

 

[Borek]

is it because the electrons could possibly collide with the oxygen and other electronegative gases, ionizing them and thus giving a smaller reading on the current meter?

More precisely "giving no reading".