Hi Shahd,

Recall that the equation used for to describe photoelectric effect is “Kinetic energy of ejected electrons = hf - work function.” Think of the metal’s work function as like a shield. Decreasing the work function would decrease the kinetic energy of the ejected electrons as you only need to hit the metal with less energized photons/laser. This is like setting aside your most powerful sword or weapon for breaking the strongest shield. However, if we increase the frequency of photons, we are also increasing the photon’s energy. When this energy hits the metal, electrons get energized and get ejected from the metal with approximately the same amount of kinetic energy as the photon (assuming no energy lost as heat). This concept ties back to the law of conservation of energy. So light energy is converted to electron’s kinetic energy.

Hope these help!

Thanks for the quick response to Shahd's question, Youssef!

I'll only add in one thing here:

Altering the work function of a particular sample of metal (say, aluminum) is pretty difficult! The work function is a property of the configuration of the atoms at the surface of a material. You can do some fancy surface chemistry to change the aluminum (for example) and alter its crystallinity at the surface, but it won't alter the work function substantially.

What I'm trying to say is this: if you want to "change the work function", you basically have to CHANGE THE METAL.

You can find a list of work functions of common metals here:

http://hyperphysics.phy-...se/Tables/photoelec.html