Potential Difference Needed (1 Viewer)

[zenger69]

On a worksheet about photoelectric effect, it asks "Explain the purpose of the power supply as it is connected into this circuit.

So I was wondering to measure the photoelectric effect, why does there need to be a potential difference going across.
Doesn't the UV hit the emitter, the emitter releases electrons and thats the current.

 

[thunderdax]

They used an applied voltage making electrons go the other way and found the stopping voltage of the circuit ie. when no electrons moved around it. I don't know why they did this instead of just measured the voltage from the circuit with no battery. The battery in the ciruit is usully shown with an arrow through it to show the voltage can be changed.

 

[zenger69]

oh ok thanks