Thanks for the quick reply, but I honestly can't get my head round what your trying to explain, currently doing AS physics so a more simplified analogy or something would be great?blue_leaf77 said:Therefore, increasing the intensity will only increase the number of liberated electrons with the individual electron's energy remains unchanged.
Higher the frequency of the wave, more is the energy carried by it. A wave with higher frequency would have more energy, and thus more energy will be transferred to the electrons.Oscar_Ross said:I don't understand how changing the frequency of a wave effects the energy transferred to electrons following E=hf, but changing the intensity doesnt? Can someone explain it please, some sort of analogy or something??
THANKS!
At the risk of getting banned from PF for ever, I'll have a shot.Oscar_Ross said:I don't understand how changing the frequency of a wave effects the energy transferred to electrons following E=hf, but changing the intensity doesn't? Can someone explain it please, some sort of analogy or something?
At one time I would have thought this, but having come across 2 photon microscopy, where two infrared photons seem to excite an atom to emit a visible photon, I'm not so sure. It would appear that one electron can absorb two photons simultaneously, so I guess the reverse could be true.MullaTheMech said:Lol so it's another question where we're not supposed to ask why? These waves are being created. Let's say by an electron moving energy levels. So jumping from a really high level to a really low level will create a high energy photon? Can one electron only make one photon per jump? .
The textbook explains the basics, for me personally to accept that something happens I have to know why else I just won't remember it!vela said:I'm sure this is explained in your textbook in detail. What do you think is happening in the photoelectric effect?
Merlin3189 said:At the risk of getting banned from PF for ever, I'll have a shot.
For a start, E=hf gives the energy for a single photon. THAT changes with frequency, but intensity just changes the number of photons with that energy. Photons with high frequency each have high energy and photons with low frequency each have low energy.
Lame analogy: dropping a brick 1m from a table to the floor. Changing the density and mass of the brick (my analogy for frequency) changes the energy of the brick. Dropping ten bricks gives 10x the energy, but it's still the same energy per brick.
I can get the same amount of energy from a small number of heavy bricks or a larger number of light bricks: I can get more energy from a lot of light bricks than a few heavy bricks, but each individual heavy brick will always have more energy than an individual light brick.
So for light, the same energy could be few high frequency photons, or many low frequency photons.
Lame analogy for frequency affecting the energy of the photon? (And physicists please excuse me here as I have no idea why it really does!)
Waves in the sea rolling onto the shore have energy - big lumps of water are lifted up and down. Each wave coming in can use the energy to move a float up and down, turning a generator and converting the wave energy into electric energy. Each wave of a fixed height can lift the float once and give a certain amount of electric energy. Waves with a higher frequency will do this more times per minute and therefore generate more electric power than waves with a lower frequency.
If that keeps you happy, good. Personally, I don't worry so much about it. But I do have to warn you that there's little in common between mechanical waves and electromagnetic waves, apart from the name and some maths. As far as I know there's nothing in sea waves nor sound waves that corresponds remotely to a photon.
MullaTheMech, you ask a very interesting question (to which I also don't know the answer!
At one time I would have thought this, but having come across 2 photon microscopy, where two infrared photons seem to excite an atom to emit a visible photon, I'm not so sure. It would appear that one electron can absorb two photons simultaneously, so I guess the reverse could be true.
(I haven't had time to go back to the real sources on this and the WikiP article Two-Photon absorption is tagged as dubious, but if necessary I can get plenty of solid references on 2 photon microscopy.)
You're right to doubt your analogy. At the introductory physics level, ##E=hf## is just an empirical fact. It was one of the first indications of quantum behavior discovered. There's really no classical physics way to explain it. Going forward, you also want to keep in mind that quantum mechanics is the more general theory, so quantum mechanics should explain aspects of classical mechanics, not the other way around.Merlin3189 said:Lame analogy for frequency affecting the energy of the photon? (And physicists please excuse me here as I have no idea why it really does!)
Be careful about what you read on the internet. There's a lot of BS out there.MullaTheMech said:They are probably right not letting people try to explain it yet. Learning from google got me into an ether theory... at least I know about that theory now.
Changing the frequency of a wave affects the energy because energy and frequency are directly proportional. In other words, the higher the frequency of a wave, the higher the energy it carries. This is because increasing the frequency of a wave means increasing the number of wave cycles per unit time, which requires more energy to maintain.
As mentioned before, the energy of a wave increases as its frequency increases. This means that if the frequency of a wave is doubled, its energy will also double.
The wavelength of a wave is inversely proportional to its frequency. This means that as the frequency of a wave increases, its wavelength decreases. This is because the speed of a wave is constant, so as the frequency increases, the distance between each wave cycle must decrease.
The frequency and energy of a wave depend on the source of the wave. For example, electromagnetic waves such as light and radio waves have higher frequencies and energies because they are produced by high-energy sources such as the sun or electrical currents. On the other hand, sound waves have lower frequencies and energies because they are produced by lower-energy sources such as vibrating objects.
Yes, changing the frequency of a wave can also affect its properties such as its wavelength, amplitude, and speed. This is because all of these properties are interconnected and depend on each other. For example, changing the frequency of a wave will also change its wavelength and speed, but it will not affect its amplitude.