Electromagnetic induction Flashcards
What is electromagnetic induction?
It’s the process of generating an e.m.f. in a conductor by moving it across a magnetic field or by changing the magnetic field around it.
What is an a.c. generator?
A device that converts mechanical energy to electrical energy by rotating a coil within a magnetic field.
How can an e.m.f. be induced in a conductor?
By moving a conductor across a magnetic field or changing the magnetic field linking with the conductor.
What factors affect the magnitude of an induced e.m.f.?
The speed of movement, the strength of the magnetic field, and the number of coils in the conductor.
What is the function of slip rings and brushes in an a.c. generator?
They maintain electrical contact with the rotating coil while allowing it to spin, producing an alternating current.
What components are used in a simple a.c. generator?
A rotating coil, slip rings, and brushes.
What does a graph of e.m.f. against time for an a.c. generator look like?
It’s a sinusoidal wave, showing positive and negative values as the direction of e.m.f. changes.
Describe the magnetic field pattern around a straight current-carrying wire.
It forms concentric circles around the wire, with the direction depending on the current direction.
How does changing the current affect the magnetic field around a wire or solenoid?
Increasing the current strengthens the magnetic field; decreasing it weakens the field.
What effect does reversing the magnetic field have on the force direction on a current-carrying conductor?
Reversing the field reverses the force direction.
How does current direction affect the magnetic field around a wire?
Reversing the current reverses the direction of the magnetic field.
Describe the magnetic field pattern inside a solenoid carrying current.
The field lines are parallel inside the solenoid, creating a strong, uniform field similar to a bar magnet.
What happens to a conductor with current in a magnetic field?
A force acts on it, causing movement perpendicular to both the current and the magnetic field direction.
What effect does reversing the current have on the force direction in a magnetic field?
Reversing the current reverses the direction of the force.
How are the directions of force, magnetic field, and current related?
They follow the left-hand rule: thumb (force), first finger (field), and second finger (current) at right angles to each other.
