Last time we saw that the minimum amount of energy needed for an electron to be liberated from the surface of a metal plate is known as the work function. 

But, here’s the thing… the work function isn’t the same for every metal… 

For instance, zinc… has this work function… where electrons need a minimum amount of energy to be emitted

But, nickel… has a greater work function… since electrons need a greater amount of energy to be emitted

And, platinum… has an even greater work function… since again electrons need a greater amount of energy to be emitted

Whereas, potassium… has a smaller work function since electrons need a lower amount of energy to be emitted (click 1 time dead trigger)

Different metals have different work functions. 

Since different metals require different amounts of energy for electrons to be removed.

And so, which of these metals has the greatest work function? 

This metal has the greatest work function…

And we know that because… 

We know that this metal has the greatest work function since electrons require the greatest amount of energy to be emitted from its surface. 

Next, different metals having different work functions has an impact on the type of light that can cause photoelectron emission. 

For instance, let’s take potassium. 

If an electron absorbs a photon with this energy… then it’ll gain enough energy to be emitted from the surface of the metal plate… 

Whereas, if we take platinum and an electron absorbs a photon with the same energy… then it won’t gain enough energy to be liberated from the surface of the metal plate…

But, if we changed the incident radiation… and the electron absorbed a photon with a greater energy… then it would gain enough energy to be liberated from the surface of the metal plate.

Because different metals have different work functions… the same incident radiation may be able to emit a photoelectron from one metal… but not be able to emit a photoelectron from another.

And so, here this incident radiation doesn’t liberate a photoelectron 

If we changed the metal and increased the work function, what kind of incident radiation would be needed to emit a photoelectron?

Incident radiation with higher energy photons would be needed to emit photoelectrons… since this metal has a greater work function.

To sum up… different metals have… 

Different metals have different work functions. 

As a result, the same incident radiation may be able to emit a photoelectron from one metal  … but not be able to emit a photoelectron from another.