Is this photoelectric effect java applet wrong? (1 Viewer)

[edd91]

http://lectureonline.cl.msu.edu/~mmp/kap28/PhotoEffect/photo.htm

As you change the wavelength, it changes the current produced, which is wrong isnt it? Current is only reliant on intensity

 

[Dash]

I can't see the image, so I'm juss gunna explain this as I know it...
The changing wavelength changes the frequency...
Changing the frequency increases/decreases the kinetic energy of the ejected electrons...
Which therefore alters the current...
You could have a light source of the highest intensity,
but its frequency is not past that of the threshold frequency to eject electrons.
So the intensity of light would not alter current...
Therefore the main determinant for current flow would be its wavelength/frequency...
Make sense?

 

[Xayma]

Originally posted by Dash
The changing wavelength changes the frequency...
Changing the frequency increases/decreases the kinetic energy of the ejected electrons...
Which therefore alters the current...

No it wouldn't. It would only depend on the amount of photons.

If two sources emit photons at the same rate, then since the photons travel at a constant c. The rate of electrons flowing will be the same. What will happen however, is that the one with the smaller wavelength will turn on and off faster, as the electrons will reach the anode quicker, and when the photons stop it will finish quicker.

 

[t-i-m-m-y]

i'm not about to bring the argument across from the OCAU forums.

but for the record, i believe the applet is right.

and edd91 forgot to state: u need to keep the intensity bar constant, and then vary the wavelength. it only occurs when intensity is kept constant

i have an explanation, but i couldn't be bothered to explain hehe, but if some1 requests i can divulge what i *think (emphasis) to be correct

 

[Xayma]

Can you please explain, cause if each electron only absorbs the photon, it wont increase current. It will switch on and off quicker but not change the current.

 

[Rorix]

i'd tend to think an increase in frequency will result in a slight increase in current

increased maxKE = slightly more electrons

 

[gman03]

increase max KE = electrons travel faster (not more electrons)

and current is proportional to the drift velocity of the electrons.

 

[Rorix]

increase max KE = electrons travel faster (not more electrons)

and current is proportional to the drift velocity of the electrons.

Increased max KE means that the electron may still reach the plate in case of a collision, I should think.

So say we had every 1 in 1000 electrons colliding with an air particle, increasing the maxKE could say halve that...a bit extra current.

Of course, not every electron is travelling at maxKE

 

[Xayma]

Increased max KE means that the electron may still reach the plate in case of a collision, I should think.

So say we had every 1 in 1000 electrons colliding with an air particle, increasing the maxKE could say halve that...a bit extra current.

Of course, not every electron is travelling at maxKE

Actually it wont work anyway if it isnt in a low pressure area, so collisions with air particles should be alot lower. Unless it starts showing striation patterns/streamers.

 

[Rorix]

ok i was wrong about the intensity=energy thing

even with a low pressure area we'd still have a few air particles and some collisions...

 

[Xayma]

Not to any significant amount, they will give up all their energy when they collide so it will affect them equally.

 

[TripleJ]

Hey Edd91, are you from OCAU?

 

[t-i-m-m-y]

yes he is.. I even posted in the pub on his thread about this