TSFX 09 Exam question

[arthurk]

Question 2 of the light and matter section
A graph shows the photoelectric effect obtained with orange light of intensity 5.0Wm^-2. The incident light is then changed to violet, also 5.0Wm^-2.
I was asked to draw the graph of the violet light, the greater stopping voltage i understand but the second part
Violet has a lower photocurrent (violet photons have more energy than orange therefore less violet photons are needed to transfer 5W)
Do we always have to consider the second part cause i've never seen it before in any other practice exam

[kurrymuncher]

Question 2 of the light and matter section
A graph shows the photoelectric effect obtained with orange light of intensity 5.0Wm^-2. The incident light is then changed to violet, also 5.0Wm^-2.
I was asked to draw the graph of the violet light, the greater stopping voltage i understand but the second part
Violet has a lower photocurrent (violet photons have more energy than orange therefore less violet photons are needed to transfer 5W)
Do we always have to consider the second part cause i've never seen it before in any other practice exam

I was just about to make a thread on this :/

Im confused too

[arthurk]

maybe the writers of that exam were being too realistic compared to vce standards

[/0]

This is my reasoning, just kind of thought it up so it might not be right

When talking about intensity it's really the same talking about energy.
In the particle model you can increase energy by doing 2 things: increase number of photons or increase their frequency
i.e., for a given amount of energy,

If you have then in 1 metre and in 1 second you have , thus
If you have a high frequency light you will need less photons to deliver the same amount of energy.

[arthurk]

Do we have to consider this in vce physics?

[/0]

I think it could probably be a left-field question, but not a very common one at that
I mean, technically it is all part of the 'photoelectric effect'