# Physics 12 Direct Current Motors. Joke of the day: An object at rest stays at rest and an object in motion stays in motion with the same speed and in.

## Presentation on theme: "Physics 12 Direct Current Motors. Joke of the day: An object at rest stays at rest and an object in motion stays in motion with the same speed and in."— Presentation transcript:

Physics 12 Direct Current Motors

Joke of the day: An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

Direct Current Electric Motor An electric motor converts electrical energy into mechanical energy An electromagnet is the basis of an electric motor A motor uses magnets to create motion. Opposites attract and likes repel. Inside an electric motor, these attracting and repelling forces create rotational motion. Direct current (DC) means the electrical current is flowing in only one direction in a circuit. Batteries are a good source of direct current (DC).

The basics: STATOR ROTOR An electric motor has two basic parts: The stationary part (external magnets, power source, brushes) The rotating part of the electric motor is called the rotor.

Parts (and function) of a DC motor: 1. DC power supply 2. Rotor (armature) 3. Commutator 4. Brushes 5. External magnets

1. DC Power Supply Aka battery To provide the current

2. Rotor (Armature) the revolving structure wound with the coils that carry the current moves under the influence of a magnetic field

Diagram: Spinning Armature

3/4. Commutator and brushes Commutator is simply a pair of plates attached to the end of the rotor These plates provide the two connections for the coil The brushes are attached to the leads from the power supply Commutator and brushes work together to let current flow from the power supply to the electromagnetic coil when they make contact with each other

Brushes attached to battery Commutator attached to rotor

5. Magnets Provides the external magnetic field Used to create a net rotational movement

A key component of motors: Torque Torque is a measure of how much a force acting on an object causes that object to rotate. The object rotates about an axis or pivot point

Torque Torque is the cross product of radius and force The units are Nm The direction is positive for ccw and negative for cw

Torque on a Current Carrying Loop In a motor….