D.C. Batteries

D.C. Batteries Points : D.C. Batteries, What is D.C. Batteries As we know that to cause the flow of electric current, electromotive force is necessary. The e.m.f. can be set up by various way such as:

1. The relative motion of conductor w.r.t. magnetic field in case of generators and transformers,
2. The difference in temperature between junctions of dissimilar metals as in the case of thermocouple. This device is seldom used because the energy developed is very small,
3. Certain materials exposed to light and similar radiation absorb energy setting an e.m.f. This effect is known as photoelectric e.g. solar photovoltaic,
4. When the crystal of certain materials such as those of quartz and Rochelle salt are subjected to physical force or pressure an e.m.f is generated across their faces. This effect is known as piezoelectric effect,
5. The electrodes of dissimilar materials immersed in electrolyte as in case of primary and secondary cells.

Now in this section, we are going to study how an e.m.f. is generated in batteries. Batteries and cells are chemical device that sets up an e.m.f. by chemical action in batteries, a chemical reaction takes place accompanied by shifts of electrons from one material to another. This chemical reaction sets up a difference of charge and thus potential between two terminals. A cell is an electrochemical device consisting of two electrodes made of different materials and an electrolyte. A battery consists two or more cells electrically connected together and packaged as single unit. Although technically a battery has two or more cells. Batteries are used in all automobiles for light and motor ignition, in portable radio and television sets in flashlights and in an increasing number of cordless application and toys.