This is a message I have received today.
> Many thanks, Mr Hwang, for this excellent simulation.  I have used a couple
previously, but this surpassed them in complexity, e.g. the velocity arrows on
the electrons - brilliant!  However, I have one query:  when changing the
photon energy (and therefore the light frequency etc.) but maintaining the
intensity, the maximum current (i.e. for positive voltages) is the same in
your simulation, but surely the same intensity means the same energy arriving
per second and if that energy is coming in larger quanta, that means there are
fewer photons;  fewer photons means fewer photoelectrons which means lower current.

Bob Haythorne

In the current verison:
The slider for "Light Intersity" does not really mean "light intensity", but for "# of emitted photons per second".
So that it is a variable independent of "photon energy".
That was what I had in mind when I designed it.

Will it be more difficult for students if it really mean "light intensity"?
In this case: I will have to change the [u]# of emitted photon[/u] when user change [u]photon energy[/u] while keep [u]light intensity[/u] the same.
Because [u]light intensity[/u] is proportional to [u](# of photon)* (photon energy)[/u].

What is your suggestions:

Should I change the lable to "average # of photon per second" (photon current)?
Or should I keep the "light intensity", but I need to change the "# of emitted photon" when "photon energy" is modified (and light intensity is not changed)