Photoelectric effect and photocurrent drop

[hayyan1]

Homework Statement

Does the photocurrent drop to zero when a potential across it is equal to the kinetic energy of electrons?, because i found this not to be the case, the photocurrent reached a steady value that didnt decrease further, as i increased the potential across the anode and cathode. I don't understand why this happened?

 

[Redbelly98]

Was the anode at + or - relative to the cathode?

 

[hayyan1]

anode voltage was increased negatively so electron should be repelled from anode in theory, but for some reason i still was obtaining positive photocurrent, maybe i should have taken much larger negative values for potential, so current would eventually become zero?, however do you think i can extrapolate (with a curve of best fit) to zero current, because my graphs are curving towards zero photocurrent.

 

[Redbelly98]

It depends. What wavelength(s) was/were used to generate the photocurrent? How high a voltage did you get to?

Extrapolating reasonably depends on whether graphing the data generates a straight line. Does it?

 

[hayyan1]

I used yellow, turquoise, green, blue, violet. it isn't ment to generate a straight line, for each frequency, the photocurrent (yaxis) is kind of meant to drop like a 1/x graph when plotted against the potential across the xaxis

 

[Redbelly98]

That's weird. I would expect current to be zero if you go high enough in voltage, but I haven't done the experiment.

Not sure what's going on.