stored Energy and butteries The energy can not be created or destroyed, but it changes its form in many ways. In a battery, the chemical form of energy saves energy for a future use in a circuit. Battery is composed of a body and two ends for connecting to terminals of a circuit. Inside a battery, chemicals reactions produce free electrons which are concentrated in one end. Batteries reaction takes place whenever a current is drawn from it. Acting like this, they have a long life for producing and storing electrical energy. In a zinc-carbon battery, a zinc rod is inserted in s, they have a long life for producing and storing electrical energy. In a zinc-carbon battery, a zinc rod is inserted in to an acid solution. By consuming zinc, hydrogen gas is released and the consequent reactions produce free electrons. Mean while some heat energy is produced. Combination of zinc and hydrogen ions, create hydrogen gas. Putting a carbon rod inside helps to have a circuit. By connecting the two rods by wire, cause a current flow through the circuit. The energy produced in such a way has enough power, turning on a lamp connected to this circuit of even a small motor. By using a large one, can even start an automobile. In a long run, zinc rod will decay and terminates the life of battery.  Some of the more common batteries are as follows: - Alkaline Type as seen in “Duracell” and “Energizer” brand, paste as electrolyte. - Lead- acid type as seen in cars are made of lead and lead oxide as electrode and a strong acid as electrolyte. This kind of batteries can produce large amount of electrons needed for surge currents. - Nickel- cadmium type uses nickel –hydroxide and cadmium as electrodes and potassium-hydroxide as electrolyte. - Zinc- carbon type is the standard form in AA, C, and D series dry-cell batteries. This kind is explained before.  Food as a source of energy Another chemical source of energy is food which is found profoundly in our planet. In a process known as photosynthesis, sun’s energy is concerted to a chemical energy in green plants. Such energy is stored in plants cells, helping it grow and proliferated. Animals by eating the grass, convert the energy to fat and meat. By eating the meat of such animals, we gain our energy to work and grow.