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 vary the voltage. Observe the resulting photo-current.