SOURCE OF CURRENT

When two conductors at different potentials are joined by a metallic wire, current will flow through the wire. The current continues to flow from higher potential to the lower potential until both are at the same potential. After this the current ceases to flow. Thus the current through the wire decreases from a maximum value to zero. In order to have a constant current the potential difference across the conductors or the ends of the wire should be maintained constant. This is achieved by connecting the ends of the wire to the terminals of a device called a source of current.

Every source of current converts some non electrical energy such as chemical, mechanical, heat or solar energy into electrical energy. There are many types of sources of current. A few examples are mentioned below:

(1) Cells (primary as well as secondary) which convert chemical energy into electrical energy.

(ii) Electric generators which convert mechanical energy into electrical energy.

(iii) Thermo-couples which convert heat energy into electrical energy.

(iv) Solar cells which convert sunlight directly into electrical energy.