Question

Which of the following can be the graph of the output from a DC generator when its field magnet is rotated ?

• A. A
• B. B
• C. C
• D. D

Answer 1

Answer:

B. B

• A DC generator equipped with a split-ring commutator produces an output electromotive force (emf) that does not change its polarity over time.

• The commutator mechanically reverses the connections to the external circuit every half-rotation, converting the bidirectional alternating current (AC) induced inside the armature windings into a unidirectional pulsating direct current (DC).

• This results in an emf profile consisting of continuous positive half-cycles remaining entirely above the time axis, which is perfectly illustrated by graph (B).