Is household alluminium foil good for observing photoelectric effect? I have built an electroscope(very primitive, just a wire and some aluminum foil). I'm thinking about using it to observe the photoelectric effect. But I don't have any high frequency wave producing equipment.
So, before I try to obtain something for that purpose, I want to know if aluminum foil used in houses is suitable for observing the photoelectric effect.
Is it covered with some kind of metal oxide or something?
Is the 'work function' of house aluminum foil similar to the pure aluminum metal?
 A: You can use aluminium foil if you just want to demonstrate the photoelectric effect, without serious measurements. Remove the oxide layer from the aluminium foil with a clean piece of sandpaper, it remains usable for half an hour or so. Then apply the sandpaper again. A cheap sterilization box, easily available online, is a convenient UV-C source (270-280 nm). The box is fairly safe because the UV leds emit light only when the box is closed. Use a thin bare metal wire to connect the aluminium foil to the electroscope, and insert another thin wire as anode.
A: Aluminum foil is covered with a layer of aluminum oxide as soon as it is exposed to air. This tendency for metals to oxidize and also to adsorb water molecules makes work functions difficult to repeatably measure when tested in air.
In addition, certain rare-earth oxides as used to coat vacuum tube emitters dramatically reduce the work function of the metal they have been applied to.
Meaningful measurements of work functions therefore require atomistically clean surfaces, which you almost never experience in contact with air.
