Name any three devices which use permanent magnets. Name some sources of direct current. [3 MARKS]
(a) 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) Stated an important advantage of alternating current over direct current.
(d) What is the frequency of A.C. supply in India ?
Question 3 Which sources produce alternating current?
Name some water sources that can be used for agriculture.