If an object lose energy when it emits light, does that energy come from the mass of the object?
Examples:
Does a flashlight lose mass when it's turned on?
Does a regular object (like a pencil or a piece of paper) lose mass when the environment is colder than the object?
If there is a loss of mass, what specific part of the atomic structure does that mass come from?
Does it come from electrons (or other particles) losing mass? (in which case it would lead to some electrons having more mass than others?)
Or does it come from whole particles being converted to energy?
Or does it come from the kinetic energy of its molecules?
Best Answer
You are being misled by some of these answers and responses. It is perfectly fine to think of the internal energy of the flashlight as real mass. Of course the percent difference in mass between a charged and uncharged battery is tiny but in principle that mass works like any other.
If you want a rough classical picture of where this mass is located think about the energy density of the fields. There is more energy in the field when a positive and negative charge are further away, and when they come closer some of this energy moves outward as an electromagnetic wave.