Magnetism and Electromagnetism - Electromagnetic Induction (Paper 2)

Question 1

what is the structure of a transformer?

Answer 1

an iron core with a primary coil on one side and a secondary coil on the other

Question 2

what does a transformer do?

Answer 2

a transformer changes the size of an alternating voltage by having different numbers of turns on the input and output sides

Question 3

how do transformers change voltages?

Answer 3

• AC 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 4

what does a step-up transformer do?

Answer 4

step-up transformers increase the voltage and have more secondary turns than primary

Question 5

what does a step-down transformer do?

Answer 5

step-down transformers decrease the voltage and have less secondary turns than primary

Question 6

what is the relationship between input (primary) and output (secondary) voltages and the turns ratio for a transformer?

Answer 6

input voltage/output voltage = primary turns/secondary turns

Question 7

what is the relationship between input power and output power?

Answer 7

primary voltage x primary current = secondary voltage x secondary current when 100% efficient