4.5.5

The d.c. motor

4 flashcards to master The d.c. motor

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Key Concept Flip

A simple d.c. motor has a coil of 50 turns carrying a current of 2.0 A within a uniform magnetic field. Suggest three modifications that would increase the turning effect (torque) on the coil.

Answer Flip

1. Increase the number of turns on the coil (

Example: to 100 turns).<br>2. Increase the current in the coil (. to 4.0 A).<br>3. Increase the strength of the magnetic field (. by using stronger magnets). <br><br>Explanation: The turning effect (torque) is directly proportional to the number of turns, the current, and the magnetic field strength. Increasing any of these increases the overall force.
Key Concept Flip

A d.c. motor uses a coil placed in a magnetic field. State three factors that affect the magnitude of the turning effect (torque) experienced by the current-carrying coil.

Answer Flip

1. The number of turns on the coil.
2. The magnitude of the current flowing through the coil.
3. The strength of the magnetic field.

Key Concept Flip

Explain how a split-ring commutator and brushes enable continuous rotation of the coil in a d.c. motor.

Answer Flip

The split-ring commutator reverses the direction of the current in the coil every half turn. This ensures that the force on each side of the coil continues to act in the same direction (either pushing up or pushing down), maintaining a constant turning effect (torque) and continuous rotation. The brushes make electrical contact with the commutator as it rotates, allowing current to flow to the coil.

Key Concept Flip

State the purpose of the split-ring commutator in a d.c. motor.

Answer Flip

The split-ring commutator reverses the direction of the current in the coil every half rotation, ensuring continuous rotation in the same direction.

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4.5.4 Force on a current-carrying conductor 4.5.6 The transformer

About The d.c. motor (4.5.5)

These 4 flashcards cover everything you need to know about The d.c. motor for your Cambridge IGCSE Physics (0625) exam. Each card is designed based on the official syllabus requirements.

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