When electrical energy is converted into thermal energy, which of the following must be true?

only the amount of electrical energy changes.
only the amount of thermal energy changes.
the total amount of thermal energy plus electrical energy changes.
the total amount of thermal energy plus electrical energy doesn't change.

I think the correct answer from the choices listed above is the last option. When electrical energy is converted into thermal energy, the total amount of thermal energy plus electrical energy doesn't change. This is base on the Law of Conservation of energy where energy cannot be created or destroyed. 

An  atom  (ours, not carroll's) consists of a positively charged  nucleus, surrounded by one or more negatively charged particles called  electrons. the positive charges equal the negative charges, so the atom has no overall charge; it is electrically neutral. most of an atom's mass is in its nucleus; the mass of an electron is only 1/1836 the mass of the lightest nucleus, that of hydrogen. although the nucleus is heavy, it is quite small compared with the overall size of an atom. the radius of a typical atom is around 0.1 to 0.25 nanometres (nm), whereas the radius of a nucleus is about 10-6  nm.  *  if an atom were enlarged to the size of the earth, its nucleus would be only 200 feet in diameter and could easily rest inside a small football stadium.read more on -

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