Applet: Photo Effect
Here you can study the photo-electric effect with three different
materials, sodium, cesium, and silver. their work functions have the
values 2.75, 2.14, and 4.26 eV, respectively. You can change the
wavelength and intensity of the light, as well as the voltage across
the agp. The resulting photo-current is indicated at the top.
You can conduct several series of experiments:
- Set the voltage to 0. Vary the wavelength. Observe the onset
of the photo-current. What are the biggest wavelengths for the
three materials, for which you still detect photo-current?
- Set the voltage to 0. Go to a wavelength bigger than the onset
poin and vary the intensity of the light? Is there ever any
photo-current? What if you raise the voltage?
- Go to a wavelength smaller than the onset value and very the
voltage. Observe the resulting photo-current.