3.7.5 - DEFINITIONS Flashcards
Back emf?
An emf generated by the coil in an AC generator that acts against the potential difference that has been supplied to the motor
Cyclotron?
A particle accelerator made up of two D shaped electrodes positioned opposite each other.
Electromagnetic induction?
When an emf is induced in a wire/ conducting rod when it is moved relative to a magnetic field
Faraday’s law?
The magnitude of the induced emf is equal to the rate of change of flux linkage through the circuit
Magnetic field line?
A line representing the path a North Pole would take when placed within the field
Lenz’s law ?
An induced current is always in a direction so as to oppose the change that caused it
Magnetic field?
A region surrounding a magnet or current-carrying wire that will exert a force on any other magnet or current-carrying wire placed within it
Magnetic flux?
A value which describes the magnetic field/lines passing through an area.
Magnetic flux density?
The force per unit current per unit length on a current-carrying wire placed at 90 degrees to the field lines
Magnetic flux linkage?
The magnetic flux multiplied by the number of turns, N, of the coil
Motor effect?
When a current-carrying wire is placed within a magnetic field (non-parallel to the field lines) and experiences a force both perpendicular to both the wire and the field lines
Step-down transformer?
A device made of two insulated wires coiled around an iron core in which the output voltage is smaller than the input voltage due to the secondary coil having fewer turns than the primary coil
Step-up transformer?
A device made of two insulated wires coiled around an iron core in which the output voltage is greater than the input voltage due to the secondary coil having more turns than the primary coil
