Question

Why are carbon brushes used in electric motors ? How does these work?

Answer 1

The diagram in ur book shows howthe commutator and brushes worktogether to let current flow to theelectromagnet, and also to flip thedirection that the electrons are flowing at just the right moment. The contacts of the commutator are attached to theaxle of the electromagnet, so they spin with the magnet.

Answer 2

The brushes are made of carbon

because carbon is a reasonably good conductor of electricity and it is soft, so it makes good contact. Carbon brushes are used in DC machine to prevent sparking due to short circuiting of the armature colls. 2 brushes are placed over the shaft they are fixed in nature Shorted current is collected from the brush terminals and it is supplied to the commutator. The commutator

makes the armature current

unidirectional in nature

In Induction motor brushes are used to conduct current from stator winding to rotor winding.They have

high resistivity and brushes are also used to collect the current by

avoiding sparking.