This applet shows you the effect of light on various metals. This is dependent upon the wavelength, and not the intensity of the light. Short wavelengths are to the left.
Long wavelengths are to the right.
Choose different metals also. Most vary in sensitivity only slightly, but some are excited by longer wavelengths. See if you can find them. Also, you may wish to determine the approximate wavelength that excites the electrons in each metal. The photoelectric effect is a very interesting discovery and can only be explained using quantum physics.