Photoelectric Effect
From Einstein’s equation:
hf = W + e*Vstop , we can see that the straight line of the Vstop vs f graph should have a slope of (h/e) . This gives a second way of determining the value of h. [The first was from fitting the blackbody curve.] When we do this, we get the same value for h that Planck did: 6.63 x 10-34 Joule*sec .