why there cause emission of light when when current that means electrons pass through the tungsten coil?

Question

electron collides with the tungsten atom, temparature then increased.Temparature causes the electron to reach the higher atomic orbit that means electron got an accelaration . Thus there is produced a magnetic field and an eletrical field and emits electromagnetic radiation . But the electron cannt go back to its original orbit unless the temparature is decreased .So my question is that why the electromagnetic radiation continues to radiate?

Answer 1

The tungsten metal has plenty of free electrons that can absorb or emit light of any frequency--not just at discrete levels corresponding to specific transitions. Consequently, you can treat it as a blackbody.

So when you run current through the tungsten wire, it heats up and releases blackbody radiation (continuous spectrum, not a line spectrum).

Also, you are misunderstanding the relationship between quantum states and temperature. Hi temperature does NOT mean that the atoms are all excited.

The quantum states in equilibrium follow a probability distribution called the boltzmann distribution, which says that the probability of being in a particular state of energy E is proportional to exp (-E/kT). So in equilibrium, you are always more likely to be in a lower energy state than in a higher one, no matter what. If kT is small compared to E, you are almost never in that state. If kT is large compared to the energies, all states are equally likely.

Answer 2

There is also line radiation, but the excited atoms aren't stable. They decay back to a ground state very soon after they are collisionally excited. They decay ties are much shorter than mean time between collisions so unless they atom has a metastable energy state, it spends most of the time in the ground state. The bulk of the radiation is due to the vibration of the atoms in the metal.

Answer 3

A tungsten coil does not glow because of line radiation, which is what you're sort of talking about. A tungsten coil glows because anything that is hot and dense emits blackbody radiation.

Blackbody is the process, not line radiation.

Answer 4

its very easy to understand this. no big deal. u said that electrons get excited in the atoms of tungsten. true. this excited state is unstable. and hence they return to their actual positions by emitting photons and thereby getting de-excited. the process continues as long as the current flows- excitement and de excitement with emission of photons. so it continues to emit light.