Theory of photo electric effect?
electrons travel around the nucleus in orbits and the farther the orbits are from the nucleus the more energy the electrons have.
electrons can go to a lower orbit or jump to higher one by release or absorption of energy. this energy is in the form of light. an electron emits a photon of a specific frequency when it goes to lower orbit and then if it absorbs another photon of the same frequency ,it will jump back to its original orbit
this is called the photoelectric effect. the frequency of light that needs to be absorbed is different for different elements and this is what helps us to identify an element just by looking at its spectrum of light frequencies absorbed.
Very energetic photons Like those from the higher frequency end of the spectrum like Gamma rays, X-rays or powerful Ultraviolet rays have so much energy that they completely knock the electron off of the atom as the electron gains a lot of energy.
this turns the Atom into an ion, a positive ion and therefore,
these waves are called ionising rays. these rays are very harmful to us as if they hit our skin, they knock off the electrons from our atoms which changes Our DNA and this Causes Cancer
the photoelectric effect is also used in many things, mainly in Solar Power Cells which uses the photons from the sun to set the electrons in motion