what is the difference between a dc motor and an ac motor?

Answer 1

There are many types of both so it cannot be expained easily the differences.

DC - Commutator (shunt, series and compound wound), Permanent magnet. Brushless.

AC - Induction (3 phase and many different single phase types), Synchronous, Wound rotor, NS (induction regulator),

Generally dc tends to have higher maintenance issues (motors tend to have brushes) and is less used than it was. Years ago it was easier to control the speed of a dc motor but modern variable drives mean that ac is often preferred.

Answer 2

The most striking difference between an AC and a DC motor is the commutation process which is a part of DC motors.

The DC quantity that you supply to a brushed DC motor gets converted into alternating quantity in the armature circuitry by the help of the Commutator and brush assembly. In case of a brushless DC motor, this takes place in the inherent driving circuit. (Commutation is periodically reversal of the current direction between the rotor/armature and the external circuit).
In an AC motor, the inversion/conversion of quantities (commutation) is not required/done.
There are lots of other constructional differences (please consult a standard text book as a detailed coverage here will be difficult) among different kinds of AC and DC motors. Although all of the machines work invariably on the principle of Faraday's law of EMI.

https://www.electrikals.com/

Answer 3

An induction motor uses a shorted rotor, and gets it's drive current to create the repulsion needed to make it turn. A DC motor is built to create the repulsion needed by virtue of the configuration of how the electromagnets are oriented in the motor. The problem with your question is that in a universal motor, it will run off of either AC, or DC voltage because it uses a commutator.