Photoelectric effect

[you0006]

I get confused here, so please don't load me up with technical jargon...I'm this close (holds fingers very close together) from burning my text book

In the photoelectric effect -- this proved
that an increase in intensity =

increase in frequency of light =


also why did this not support the wave model?


Cheers guys

[Lasercookie]

Increase in intensity = increase in frequency of light? What!

The frequency of light determines the colour. Say you have a red light. You can shoot that red light at the surface. You can then change the intensity and what happens will change. The frequency stays the same.

Are you perhaps talking about how increasing the intensity will increase how fast that electrons are emitted ("the photocurrent").

Waves consider intensity and frequency are different things. Frequency is frequency (which is linked to period, velocity and wavelength (f=1/T and v=f x wavelength). Intensity is linked to the amplitude and amplitude is also linked to the energy carried in the wave.

However, this does not fit with experiment. Experiment showed that intensity is independent of the energy, changing it has no effect on the kinetic energy given to the electron. This is one of the reasons why the wave model failed.

The other reasons were to do with frequency. Like I said earlier, waves link energy to the amplitude, not the frequency. But we know that E=hf. Increasing the frequency will increase the energy.

Waves cannot explain this. Wave model could not also explain the fact that different metals had threshold frequencies that differed. 

I have tried to state things as simply as possible. If this was accidentally too technical, and you don't understand the words I used, you need to go learn them. The only jargon words I think I used are:
--Frequency
--Intensity: measured in lux - you would have dealt with this in Unit 3: Electronics and Photonics. I don't think we'll need to crunch numbers with things to do with intensity.
--Wavelength
--Wave model
--Particle Model (or "photons")
--Energy
--Amplitude
--Electron
--Threshold frequency: the minimum frequency at which an electron will be ejected

You should also be familiar with the formulas.

If you're still having trouble, I think this is a good simulation of the photoelectric effect: http://phet.colorado.edu/en/simulation/photoelectric. Have a play around with it.

[tony3272]

Increase in intensity = increase in frequency of light? What!

The frequency of light determines the colour. Say you have a red light. You can shoot that red light at the surface. You can then change the intensity and what happens will change. The frequency stays the same.

Are you perhaps talking about how increasing the intensity will increase how fast that electrons are emitted ("the photocurrent").

Waves consider intensity and frequency are different things. Frequency is frequency (which is linked to period, velocity and wavelength (f=1/T and v=f x wavelength). Intensity is linked to the amplitude and amplitude is also linked to the energy carried in the wave.

However, this does not fit with experiment. Experiment showed that intensity is independent of the energy, changing it has no effect on the kinetic energy given to the electron. This is one of the reasons why the wave model failed.

The other reasons were to do with frequency. Like I said earlier, waves link energy to the amplitude, not the frequency. But we know that E=hf. Increasing the frequency will increase the energy.

Waves cannot explain this. Wave model could not also explain the fact that different metals had threshold frequencies that differed. 

I have tried to state things as simply as possible. If this was accidentally too technical, and you don't understand the words I used, you need to go learn them. The only jargon words I think I used are:
--Frequency
--Intensity: measured in lux - you would have dealt with this in Unit 3: Electronics and Photonics. I don't think we'll need to crunch numbers with things to do with intensity.
--Wavelength
--Wave model
--Particle Model (or "photons")
--Energy
--Amplitude
--Electron
--Threshold frequency: the minimum frequency at which an electron will be ejected

You should also be familiar with the formulas.

If you're still having trouble, I think this is a good simulation of the photoelectric effect: http://phet.colorado.edu/en/simulation/photoelectric. Have a play around with it.

I think they meant:
Increase in intensity=  (Fill in the gap)


Increase in frequency of light = (Fill in the gap)

[Lasercookie]

I think they meant:
Increase in intensity=  (Fill in the gap)


Increase in frequency of light = (Fill in the gap)

Oh of course.

Anyway, I addressed that in my answer.

[you0006]

wow laser, someone knows their stuff!

[Lasercookie]

wow laser, someone knows their stuff!

More importantly, were you able to make any sense of it?

[you0006]

Not as yet...I'm trying to condense it a bit. but i get muddled