15 Electromagnetic Induction

Question 1

Voltage is induced in a conductor or a coil when

Answer 1

It moves through a magnetic field or when a magnetic field changes through it

Question 2

Factors that affect size of voltage induced

Answer 2

• speed of wire
• number of turns
• size of coils
• strength of magnetic field

Question 3

Describe the generation of electricity by rotation of magnet within a coil

Answer 3

• coil is rotated within a magnetic field
• coil cuts the magnetic field line
• this induces a voltage in coil

Question 4

Transformers changes size of an alternating voltage by

Answer 4

Having different numbers of turns on the input and output sides

Question 5

Structure of transformer

Answer 5

• alternating current in the primary coil produces a changing magnetic field around the primary coil
• the iron core channels the changing field through the secondary coil
• the changing magnetic field induces a voltage in the secondary coil

Question 6

If there are more coils in the secondary

Answer 6

Voltage increases (step up)
Because power is conserved and p=iv current decreases

Question 7

If there are more coils in a primary

Answer 7

Voltage decreases (step down)
Current increases

Question 8

Step up transformers increase voltage as there’s

Answer 8

More secondary turns than primary

Question 9

Step down transformers decrease voltage as theres

Answer 9

More primary turns than secondary

Question 10

Input (primary) voltage / output (secondary) voltage =

Answer 10

Primary turns / secondary turns

Question 11

For 100% efficiency

Answer 11

Input power = output power
Primary voltage x primary current = secondary voltage x secondary current

Question 12

For 100% efficiency

Answer 12

Input power = output power