P3 - Electromagnetic Induction

Question 0

What are the 2 main methods of electromagnetic induction?

Answer 0

Moving a magnet through a coil of wire

Turning a magnet end to end in a coil of wire

Question 1

What is electromagnetic induction?

Answer 1

The creation of a voltage across a conductor which is experiencing a change in magnetic field

Question 2

Describe how moving a magnet through a coil of wire induces a voltage

Answer 2

You move a magnet through a coil of wire to induce a voltage and then move it through in the other direction to induce a reversed voltage to the one just induced

The constant change of direction of current causes an alternating current (AC)

Question 3

Describe how turning a magnet end to end inside a coil of wire induces a voltage

Answer 3

As you turn the magnet, the magnetic field through the coil changes which induces a voltage in the coil of wire

After half a turn, the direction of the magnetic field in the coil reverses so the direction of the current reverses until the turn is completed

This creates an alternating current

Question 4

What are transformers?

Answer 4

Transformers use electromagnetic induction to change voltage in an AC current

Question 5

Describe how transformers work

Answer 5

An iron core has 2 coils of wire around it called the primary and secondary coil

The primary coil produces a magnetic field that stays within the iron core and nearly all of it passes into the secondary coil

Because there is AC in the primary coil, the field in the iron core is constantly changing direction. This changing magnetic field causes an AC current in the secondary coil

No electricity flows round the iron core because it purely transfers the changing magnetic field

Question 6

What are the 2 types of transformer and what is the difference between them?

Answer 6

Step-up transformers increase the voltage and decrease the current

Step-down transformers do the opposite

Question 7

How is the voltage changed by a transformer?

Answer 7

If there are more coils on the secondary coil than the primary coil, the voltage is stepped up

If there are less on the secondary coil, the voltage is stepped down

Question 8

What is the transformer equation?

Answer 8

Voltage in primary coil / voltage in secondary coil = coils on primary coil / coils on secondary coil

Question 9

What are switch mode transformers?

Answer 9

Transformers that operate at higher frequencies than traditional transformers meaning they are useful for chargers for home devices