Ch-13 Magnetic Effects of Electric Current (Question) Page237

Question 1:	State the principle of an electric generator.
Answer :	An electric generator works on the principle of electromagnetic induction. It generates electricity by rotating a coil in a magnetic field.
Question 2:	Name some sources of direct current.
Answer :	Some sources of direct current are cell, DC generator, etc.
Question 3:	Which sources produce alternating current?
Answer :	AC generators, power plants, etc., produce alternating current.
Question 4:	Choose the correct option. A rectangular coil of copper wires is rotated in a magnetic field. The direction of the induced current changes once in each (a) two revolutions (b) one revolution (c) half revolution (d) one-fourth revolution
Answer :	(c) When a rectangular coil of copper is rotated in a magnetic field, the direction of the induced current in the coil changes once in each half revolution. As a result, the direction of current in the coil remains the same.