6.3: Electromagnetism

Question 1

Faraday’s law

Answer 1

The magnitude of the induced EMF is directly proportional to the rate of change of magnetic flux linkage.

Question 2

Field lines

Answer 2

Lines that show the direction in which a magnetic North monopole would experience a force if placed at that point in a field.

Question 3

Fleming’s left hand rule

Answer 3

The relative direction of motion, field direction and current direction in the motor effect can be represented by the thumb, first finger and second finger of the left hand respectively. For the motion of a charged particle in a magnetic field, its direction replaces the current direction.

Question 4

Force on a charged particle

Answer 4

A charged particle moving through a magnetic field will experience force equal to the product of the charge, its velocity and the magnetic flux density.

Question 5

Force on a current-carrying conductor

Answer 5

A current-carrying conductor will experience a force when placed in a magnetic field. The direction of the force can be determined using Fleming’s left hand rule.

Question 6

Lenz’s law

Answer 6

The direction of an induced current is such that it opposes the current that created it.

Question 7

Magnetic field

Answer 7

A region of space in which magnetic materials and moving electric charges feel a force.

Question 8

Magnetic flux density

Answer 8

The force per unit current per unit length on a current-carrying wire placed at 90 degrees to the field lines. Sometimes also referred to as the magnetic field strength.

Question 9

Magnetic flux linkage

Answer 9

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

Question 10

Magnetic flux

Answer 10

A value which describes the magnetic field or field lines passing through an area. It is the product of magnetic flu density and the perpendicular area it passes through.

Question 11

Tesla

Answer 11

The unit of magnetic flux density

Question 12

Transformer

Answer 12

A device used to increase or decrease the voltage with two sets of coils with different numbers of turns wrapped around a magnetic core. The transformer is step-up if the number of coils on the secondary coil is greater than the number on the primary coil. The transformer is step-down if the number of coils on the secondary coil is fewer than the number on the primary coil.

Question 13

Velocity selector

Answer 13

A combination of a magnetic field and an electric field, which results in charges passing through and leaving with a specific velocity.

Question 14

Weber

Answer 14

The unit of magnetic flux.