What do you understand by the terms ‘direct current’ and ‘alternating current’? b) Name some sources of direct current and some of alternating current. c) State an important advantage of alternating current over direct current. What is the frequency of AC supply in India?

1. When the current flows in just one direction, it is known as direct current while the flow of current in revsere direction at equal intervals of time is known as alternating current.
2. Sources of DC are: dry cell and car battery

Sources of AC are: AC generator and bicycle dynamos

1. An important advantage of AC over DC is that the transmission of AC over a long distances is much easier without much loss in electrical energy.