Question

Name some sources of direct current and some of alternating current.

Answer 1

Hint: The Direct Current and Alternating Current are produced by generators or dynamos by almost similar techniques. Also, there are other methods such as chemical reactions which result in electrical energy that can be used for various purposes.

Complete answer:
The sources of electricity based on the type produced are:
- Sources of Direct current: Commutator-based dynamos, chemical cells and batteries, solar cells
- Sources of Alternating Current: Generators, Hydroelectric plants, wind turbines
The production of Electric energy in any form requires the harvesting of another form of energy. Some techniques can develop both forms of electric current by slight modifications as in a generator, a solar cell or a windmill.
Let us discuss the different sources based on the energy form from which current is converted.
A.Mechanical energy: The generators and dynamos use the mechanical energy to produce electric energy. A rotating metal strip with wire in a magnetic field induces current in the wire which is extracted and used by us. Introducing a commutator in the arrangement results in the DC current. A commutator helps in keeping the direction of flow current constant. Without which, the resulting current is AC.
B.Chemical energy: The batteries we use from the smallest AAA to large ones in the motor vehicles use chemical reactions to produce energy for electric energy. Most chemical reactions include production ions which introduces an electric flow in the system. The primary cell (Zinc – carbon dry cell), rechargeable secondary cell (Lead – acid cell), Hydrogen fuel cell, Nickel – Cadmium cell are the widely used sources of DC current employing chemical reactions.
C.Solar cells and Wind mills: The solar cells store energy in the form of DC current which can later be modified to use as AC current. The windmills generate AC current if the modification for DC current is not employed.
These are the various sources of electric current.

Note:
There are many available sources which can be converted to electrical energy. The inadequacy of technology, requirement of massive infrastructure, heavy machinery and large capital investments are factors which inhibit the full utilisation of natural sources such as solar and wind energy. The Hydro-electric power plants provide mechanical energy.