dc Motog

Question 1

Magnets (stator) description

Answer 1

Either permanent magnets or
electromagnets on opposing sides of rotor (armature) - often referred
to as the stator.
Usually curved

Question 2

Magnets (stator) role

Answer 2

Provides external magnetic field which interacts with the current in the coils to produce the motor effect.

Question 3

Iron core description

Answer 3

Cylinder of laminated soft iron around which rotor coils are wound.
- Mounted on the axle, in the rotor.

Question 4

Iron core role

Answer 4

Concentrates the external
magnetic field to maximize torque.
- Laminations limit the size of eddy currents.

Question 5

Magnets (stator) role

Answer 5

Provides external magnetic field which interacts with the current in the coils to produce the motor effect.

Question 6

Split ring commutator description

Answer 6

Two metal half rings connecting either end of the rotor coils.
- In contact with the brushes.

Question 7

Split ring commutator role

Answer 7

• Provides points of electrical contact between the coils and external circuit through the brushes.
• Breaks the electrical supply (through air gap) and reverses the rotor current every half turn to ensure unidirectional torque.

Question 8

Rotor (armature) description

Answer 8

• Usually, several coils of insulated wire are wound around the iron
  core.
• Either end is attached to one half of the commutator.

Question 9

Rotor (armature) role

Answer 9

Transmits current which interacts with the magnetic field to provide torque

Question 10

Brushes description

Answer 10

Spring loaded graphite (carbon) blocks mounted on either side of the commutator.

Question 11

Brushes (role)

Answer 11

• Points of electrical contact between the rotor and circuit (battery).
• Allows free rotation of the coils without tangling the circuit.