Why does reflected light have a phase change of pi at the atomic level?

[mkbh_10]

Please explain the phenomena of reflection at atomic level ?

We know that on reflection a phase change of pi occurs i/e phase difference b/w reflected & incident beam is pi , explain this phase change of pi at atomic level ? What is actually meant by phase change atomic level ?

 

[pam]

1. The phase change on reflection between two dielectrics is either pi or zero, depending on
n'-n.
2. The reflection is determined by the bulk material, and not on an "atomic level".

 

[mkbh_10]

But something must happen at atomic level , then only it will happen in bulk material

 

[lightarrow]

But something must happen at atomic level , then only it will happen in bulk material

But in this case "the result of the sum is not the sum of the results". pam is right. Example: can you say the temperature of an atom? It's impossible because temperature is (as reflection) a collective behaviour of many atoms, so what happens to light interacting with a single atom is not the same to what happens when it interacts with many atoms. Certainly, however, something do happen to every atom: the electromagnetic wave perturbs the atom's electrons which, in turn, generate another wave; all the waves generated by the many atoms add up forming a resultant wave which has the properties you have studied. All these waves are electromagnetic fields, which have to obey Maxwell's equations; from those conditions you have the phase displacement; note that the effect is not peculiar of electromagnetic waves, but of waves in general which have to satisfy the same conditions.