Experimental arrangement of photo current

Question

In my book it say that between the cathode and anode there exist number of electrons which make the space charge.
When light falls on cathode photoelectrons are released but is repelled by the space charge.
When the potential between the anode and cathode is decreased the effect of space charge becomes negligible and the electron is able to reach the anode.
The current then becomes constant and is known as saturated current.
So my questions are:

When the potential difference is increased the electric field between the plates increases so shouldn't the electron reach the anode faster or in other words shouldn't photocurrent increase with increase in potential difference?

Because of the electric field can the electrons be emitted from the metal even if the energy of the light is less than the work function?

Bhaskar0120 · Accepted Answer

I'll answer the second question first. Electrons can jump even without light, though we need a very high potential difference between the plates (about $10^{12}MV/m$ ). So even if the energy of light is less than the work function you can, in principle, emit electrons from a metal surface.

Now this answers your first question. Yes indeed higher potential would make the electrons move faster, but there are only so many free electrons in the tube. You would have to increase the number of free electrons in the tube for them to reach the other plate in the first place. To increase the number of electrons you must increase the intensity of light and that would increase the current.

trula · Answer

I never heard of electrons in a vacuum tube.
the number of e freed by the light is limited by the intensity of th light, if you increase it the current increases, the speed of the e is rather large so it does not play a big role.
only with very high power electrons ar emitted from the metal. in your tube you work with very small power.

Experimental arrangement of photo current

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