It is a guess or prediction of what may happen if you do something.
ex. I hypothesize that I will slip if i step on a banana peel.
PS A hypothesis is not always correct!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Assuming you know what your experiment is, your hypothesys, or what you predict will happen.
A lightbulb usually won't use thermal energy, only electrical energy. By conservation of energy, if 10% of the electrical energy is converted into radiant energy, the remainder is wasted - basically as heat.