What's a DC motor? What's it used for? How does it work?

Answer 1

a motor regardless of ac or dc is a gadget that transforms electrical energy to mecanical movement(spin)
not to be confused with a generator which is the reverse, it converts movement into electrical energy.
it is used in anything that needs a circular movement or any other movement. like drills,winches or toy cars.
it works on the principal that when you pass a current(electrial not black.) coil of wire a magnetic field is generated and the like poles of a magnet repells each other. so when the wire is coiled a round a shaft and an electrical current is passed through the wire, the magnets will repell the coils and the shalf will spin.
God bless,
gabe

Answer 2

A DC motor runs off direct current electricity, like ordinary batteries.

One of the coolest applications I saw recently on NOVA was an electric postal mail truck that was equipped with three DC motors and lots of big batteries. This specially built postal truck had so much torque (the forces that give it acceleration) from the DC motors that they kept breaking the drive train when tested. And that's the major benefit of DC motors, they provide more torque than comparable other motors, like AC motors.

All electric motors, AC and DC, work by taking advantage of the fact that electrical and magetic forces are just different forms of the same force (the so called electro magnetic force). The DC motor is made of a rotor (which rotates...duh) and a stator (which doesn't). When DC current is put into the stator, the rotor is pulled around to align itself with the magnetic force of the stator.

BUT (and this is a big BUT), just before the rotor aligns itself with the stator's magnetic flux, contacts (little switches) on the rotor reverse the polarity of the magnetic flux so the rotor is now pushed rather than pulled. The rotor then swings to the other side of the stator, where the polarity is again reversed to send the rotor back again.

In sum, the DC motor works because its rotor keeps trying to align itself with the magnetic flux of the stator. But just before it gets in alignment, the stator's polarity switches and the rotor has to keep on moving to the other side. In the end, the rotor just keeps on rotating in a vain effort to align itself with the stator's flux.

Answer 3

DC motors are different from AC motors in they have commutators instead of sliprings. They are also easier to control speed since AC motors require a change in frequency as well as voltage. But they are usually more expensive than AC. The advent of inverters, and VFD's (Variable frequency drive) are making AC motors a preferred method of varied speed applications.
Like its name implies, DC motors run on direct current instead of alternating current. The current is sent to brushes which slide against a commutator. The commutator is attached to the armature, which (usually) rotates inside the field. As current goes through the armature, it generates a magnetic field and is repelled by the magnetic flux of the "Field"(The stationary portion of the motor surrounding the armature) One pole of the field has a North magnetic polarity and the other pole has a South polarity. The armature is attracted to one side and repelled by the other. It of course rotates to the position it is attracted to, however when it gets there, the commutator reverses the magnetic flux on the armature and it has to go around again, completing the cycle.

In mechanical terms the armature is called the rotor and the field is called the stator.

Answer 4

Any electric motor that runs on batteries is a DC motor.

Answer 5

Because of the low voltage it can be used for stepping.
In other words quick off and on use.