P4.5.1 - Electromagnetic Induction

Question 1

When is the emf induced in a conductor? [2]

Answer 1

whenever there is relative movement between the conductor and a magnetic field

Question 2

When is the emf induced in a conductor (examples)? [2]

Answer 2

• the conductor moves in a stationary magnetic field
• the conductor is stationary in a changing magnetic field

Question 3

How is emf induced due to a moving conductor? [2]

Answer 3

the conductor (e.g. wire) cuts the field lines and induces the emf in the wire

Question 4

How is emf induced due to a moving magnetic field? [2]

Answer 4

• as the magnet moves through the conductor, the field lines cut through the turns on the conductor causing the emf to be induced

Question 5

What are the factors that will increase the induced emf? [3]

Answer 5

• strength of the magnet
• speed of the movement of the magnet through the coil
• length of conductor/coil (adding more turns)

Question 6

Where is electromagnetic induction used in? [2]

Answer 6

• electrical generators which convert mechanical energy to electrical energy
• transformers which are used in electrical power transmission

Question 7

What is an experiment that shows the phenomenon of electromagnetic induction? [1]

Answer 7

a magnet and a coil

Question 8

Describe the basics of the experiment. [2]

Answer 8

• coil connected to a sensitive voltmeter and a bar magnet is used to induce the emf

Question 9

What happens when the bar magnet is stationary in the experiment? [3]

Answer 9

• voltmeter shows a 0 reading
• when bar magnet held still, inside or outside, there is not magnetic field lines being cut
• no emf is induced

Question 10

What happens when the bar magnet is moved inside the coil in the experiment? [3]

Answer 10

• as the bar magnet moves, the magnetic field lines are cut by the coil
• induces the emf
• shows reading on voltmeter

Question 11

What happens when the bar magnet is moved out of the coil in the experiment? [3]

Answer 11

• as the bar magnet changes direction, the direction of current changes
• emf is induced in the opposite direction
• shown by voltmeter with the opposite sign

Question 12

What are factors affecting the direction of the induced emf? [2]

Answer 12

• switching the poles of the magnet
• the direction in which the wire, coil or magnet is moved