- #1

crick

- 43

- 4

This current is opposite to the "normal" photocurrent and its effect is to make the I-V curves not going but keep decreasing (slightly).

Suppose that one wants to determine $h$ using two different led's of frequencies ##\nu_1## and ##\nu_2## using the following method (I know about other methods but I would like to know about this one).

Let's call ##V_{0_1}## and ##V_{0_2}## the values of ##V## where the (total) photocurrent is ##0## (for led ##1## and led ##2##). And suppose that the relation used is $$h=\frac{e(V_{0_1}-V_{0_2})}{(\nu_2-\nu_1)} \tag{1}$$

(work function is not involved at all)

My question is: under what theoretical assymptions and explanations is ##(1)## suitable to calculate ##h## (i.e. when to determine ##V_0##, even if current does not go asymptitically to zero but becomes negative, is still a good method to determine $h$ using ##(1)##)?

My guess is that this is a "good" method only if ##V_0##Vis such that it "brakes" all the electrons always in the same way, i.e. it makes them reach the same kinetic energy, for any frequency ##\nu## that is being used.

But how is this confermed/denied theoretically?