3.7.5 - DEFINITIONS

Question 1

Back emf?

Answer 1

An emf generated by the coil in an AC generator that acts against the potential difference that has been supplied to the motor

Question 2

Cyclotron?

Answer 2

A particle accelerator made up of two D shaped electrodes positioned opposite each other.

Question 3

Electromagnetic induction?

Answer 3

When an emf is induced in a wire/ conducting rod when it is moved relative to a magnetic field

Question 4

Faraday’s law?

Answer 4

The magnitude of the induced emf is equal to the rate of change of flux linkage through the circuit

Question 5

Magnetic field line?

Answer 5

A line representing the path a North Pole would take when placed within the field

Question 6

Lenz’s law ?

Answer 6

The direction of induced emf is such that it will oppose the change that is producing it

Question 7

Magnetic field?

Answer 7

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

Question 8

Magnetic flux?

Answer 8

A value which describes the magnetic field/lines passing through an area.

Question 9

Magnetic flux density?

Answer 9

The number of magnetic flux lines passing through a region of space per unit area

Question 10

Magnetic flux linkage?

Answer 10

The magnetic flux multiplied by the number of turns, N, of the coil

Question 11

Motor effect?

Answer 11

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

Question 12

Step-down transformer?

Answer 12

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

Question 13

Step-up transformer?

Answer 13

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

Question 14

Eddy currents?

Answer 14

Looping currents induced by the changing magnetic flux in the core. They reduce magnetic field strength by creating a magnetic field that acts against the field that induced them

Question 15

(one) Tesla?

Answer 15

The flux density that causes a force of 1N on a 1m of wire carrying a current of 1A at right angles to the flux