Is there any diffrence in mass of a new bulb and a used bulb?

Question

A new bulb glows its expected span of life. After its full use the bulb is not broken and nothing entered or came out of it except light. I am just curious to know whether weight of the new bulb and the used bulb is the same or diffrent.

If there is any diffrence than it must be becouse of the mass lost in the form of photons. The diffrence may be very small and may be difficult to find out. Have any body done this before?

Any diffrence means photons have mass.

Addiotional Comments;

It suggests that the light and heat is due to electrons entering into the bulb filament. Hence no loss of mass. But here again I express muy doubt about the actual loss of mass in emission of light. Additional electrons entering the bulb means additional mass. can any body give a correct balance sheet of the mass gained or lost?

Answer 1

Hi Alice,
The bulb is sealed so no matter is leaving the bulb. It weighs the same.

You are passing current through the Tungsten filament to excite the electrons. As the electrons relax they emit a photon of light.

As an aside, you will notice that old bulbs are often darker than new bulbs. This is because some of the Tungsten metal has vaporized and been deposited onto the glass.

If you like this kind of stuff consider studying Chemistry. It's very interesting.

Answer 2

There should be no difference in mass or weight of a new bulb, versus a used bulb. The element in the bulb after its lifespan just burns out causing the bulb to produce no more light. Therefor, the particles of the element are still inside the glass of the bulb, weighing the same as they did from the start, they are now just no longer connected.

Answer 3

No, there shouldn't be any differences. When you mention light and photon, you must be considering the mass of light particle. Well, If you are really critical about the unmeasurable minute lost of light travel through the glass bulb, not much is lost. Even if you understand the nature of electrons and electricity there really isn't much lost. Let me explain to you about the nature of the working electron and heat. When you apply an electrical source to say a piece of wire like in the light bulb, what happens is you are forcing very high current flow of electrons through that piece of wire. And in order for this to happen the few electrons travel through the wire has to bump the next electron an so on to cause the flow. It's like you have many marbles all lined up in one straight line on the floor. To move the very first one, you have to cause the first one to bump the next one so that the last one can be bumped back to the source. when this happens really fast and you have tons of electrons flowing through a piece of wire, it causes high friction because eletrons are bumping into each other. Anytime you have friction due to forces from say kinetic forces (like movement of electrons), this produces heat. To make the long story short, when enough heat is produce by elctrons bumping into each other causing friction, through a piece of wire, these electrons will emit light just as a piece of metal glowing red when you heat it in fire.
As you can see nothing is lost other than heat lost. The only measurable thing is heat lost while the light bulb still glows. Since heat is measured in an energy quantity, there is no mass to be accounted for, and mass is measured in weight unit.
If you truly are interested in what I just tell you, you should consider studying physics. You will learn all these in college.

Answer 4

No difference. Some of the tungsten in the filament evaporated from it and was deposited on the bulb. The (tiny!) mass lost from the bulb's radiation [E = m c squared] is supplied from the energy supplied to illuminate it.

Answer 5

Yes there must be diffrance between the mass of two of them.The used bulb have low mass in comparison to newer bulb as the tungston filament is burned out and it gradully grows thin and the bulb fuses.So there is negligible diff. between the masses of two of them but yes there is diffrance.

Answer 6

I'd like to hear the EE prof explain what happens to the atoms that have left the tungsten filament but are still locked inside the (evacuated) light bulb.
They didn't "burn up", and they didn't "leak out". So, dot dot dot

Answer 7

Yes. used bulbs should weigh less.

Answer 8

Just follow the light...

Answer 9

i Guess Not!