Transformers

Question 1

What are transformers?

Answer 1

Devices that change the voltage in an electric circuit

Question 2

How do transformers work?

Answer 2

A transformer consists of a primary coil, secondary coil and a soft iron core (easily magnetised). When an AC is supplied to the primary coil, an alternating magnetic field is produced around it. This changing magnetic field causes an alternating p.d to be induced in the secondary coil. A current is not produced in the secondary coil when a DC is supplied to the primary coil

Question 3

Step-up transformers

Answer 3

-more turns on the secondary coil than the primary coil
-increases the p.d, decreases the current (V is inversely proportional to I)

Question 4

Step-down transformers

Answer 4

-more turns on the primary coil than the secondary coil
-decreases the p.d, increases the current (V is inversely proportional to I)

Question 5

Number of turns on a transformer equation

Answer 5

Vp / Vs = Np / Ns

Question 6

Power transmission in a transformer

Answer 6

Electrical power is transferred from the primary coil, to the secondary coil. If the transformer is 100% efficient, all of the power which is supplied to the primary coil is transferred to the secondary coil

Question 7

Current-p.d transformer equation

Answer 7

Vp x Ip = Vs x Is