Question

Which of the following statements is correct?
A) AC generator generates a higher voltage
B) DC generator generates a higher voltage
C) AC generator has a permanent magnet whereas a DC generator has an electromagnet
D) There is a split-ring commutator in a DC generator but not in an AC generator

Answer 1

Hint: A device that converts mechanical energy into electrical energy is called a generator. It uses the principle of electromagnetic induction to generate electricity. When a conductor is placed in a varying magnetic field or the magnetic field is kept stationary and the conductor is moved there will be an induced electromotive force. This process is known as electromagnetic induction. DC generators produce direct current and AC generators produce alternating current.

Complete step by step solution:
AC generators convert mechanical energy into electrical energy in the form of an alternating sinusoidal waveform. DC generators produce direct current from mechanical energy.
The voltage generated by both AC and DC generators depends on the flux density associated with the coil. Hence we cannot say whether AC or DC generators produce more voltage.
Both AC and DC generators are usually made of permanent magnets.
DC generators have split-ring commutators. But in AC generators instead of commutators slip-rings are present.

So, the answer is Option (D): There is a split-ring commutator in a DC generator but not in an AC generator.

Note: In AC generators the coil is fixed and the magnet is moved. The construction is very simple. DC motors have a complex design with commutators and split rings. In an AC generator, the direction of the electric current reverses periodically. The current flows in one direction in DC generators. The energy loss is very less in AC generators hence they are very efficient. In DC generators due to sparking, eddy current, mechanical losses, and hysteresis loss, the efficiency is less. AC generators are low maintenance while DC motors require frequent maintenance.