Question

Calculate the energy released in joules from a 3v battery that operates a light bulb. The current flowing through the light bulb is 0.60 A and the bulb is left on for only 30s

Answer 1

Energy is power times time. the power can be found as:

$$P=UI.$$

Then the energy will be

$$E=Pt=UIt=3\cdot0.6\cdot30=54\text{ J}.$$