Electrons are tiny particles within atoms that have a minute electric charge. Chemical energy is the source of power in batteries. Atoms from one metal travel through the acid to the other metal, releasing electrons. Eventually, when all the mobile atoms have been transferred, no additional electrons may be released, and the battery is dead.
Engineers make measurements when they are working with electricity.
They measure voltage, current, resistance and power. The entire process converts electrical energy to light energy and heat energy. To calculate how many lemons it would take to run an electric car. Explain that electric cars run on very large batteries and not internal combustion engines like regular cars. Show the students a typical alkaline battery.