u know that light is an elctromagnetic wave. so what heppens to the electrons due to that?When light falls on an object what happens to the lectrons of the object?
Light falling on a metal can cause electrons to be ejected from the metal. This is known as the photoelectric effect.
Solar cells use this effect to create energy from the sun's rays
Other uses and a more indepth explanation can be foind on wikiWhen light falls on an object what happens to the lectrons of the object?
the electron basicly aborb the photon. Then the electrons are at a higher state. At this point they can reemit the photon either imediately or after a little bit.
If the eletron goes from state A to state B when it absorbs the photon it can dexcite in the same way and emit a photon of the same energy. (this is the reflection that makes metals shinny)
Or it can dexcite by going from state B to C to A, and then it will emite two photons of two differant energyies. (this is why objects have colors)
If the photon energy is large enouph then the electron will be so excited that it will escape the atom that it sits in and fly away (this is the photo electric effect).
another thing that can happen is that if the electron stays in that ecited state for a minute and another photon comes allong and stimulates the electron to dexcite then it will emite a photon of the same wavelength in the same direction. This will only happen if it is a very spicific wavelength of light that stimulates the emmition. In this case you can get Light Amplified Stimulated Emmition of Radiation (LASER).
There are other things that can happen too.
Ur question relates to photoelectric effect
It states that when light of SUITABLE FREQUENCY and WAVELENGTH falls on a metal surface electrons are ejected which r known as photoelectrons.
this effect supports the particle theory of light
u can get the details on the net.
I guess u must know about the dual nature of light. If not we can talk bout it later
Aaahhhh.... Good old quantum stuff...
What happens depends on the wavelength of light hitting the object and the material itself. Not all wavelengths will make all materials do neat stuff. When a photon of the correct wavelength comes into contact with a given electron the electron ';jumps'; energy states (called quanta). Now, there are several different energy states, and what state the electron went to will dictate what it does. There are also some things called intersystem crossing and some other, more technical stuff that I won't go into.
But, alas, the universe is a lazy place. Electrons don't like being all wound up with nowhere to go! So, they spit back out that photon. Often this happens so fast that it can be a real pain to detect in a lab without good equipment. The photon emitted is the same wavelength and, therefore, energy as the one that was originally absorbed. Neat huh?
let's talk about glow in the dark stuff for a second. You know, toys and things that you hold up to a lightbulb for a few seconds and then they glow in the dark afterward. The reason they glow is because of this reaction. Its called phosphorescence. What happened is that the visible light stimulated the electrons to a higher energy state. Even when the light stimulation was removed from the object the object kept emitting photons slowly as its electrons relaxed back to baseline.
Flourescence works the same way, except that, by definition, the object quits emitting electrons as soon as the light source is removed.
Now, for your question about metals, its how photovoltaic cells work. Certian metals produce a voltage when stimulated by certian wavelengths of UV/Vis light. Like some solar panels. Some (but not all) metals produce instantaneous flourescence and, therefore, add to their natural shinyness and light scattering properties. It can be hard to tell which is flourescence and which is merely scattering without using the spectrum outside of the visible.
Oh, and one more thing! Light doesn't have to be visible light to cause electrons to jump energy levels. Anywhere can work but, once again, its material specific.
This principal of physics and chemistry is widely used in analytical chemistry for identifiying substances both quantatively and qualatatively.
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