What is the function of a transformer?
To transfer magnetic fields
To connect separate circuits together
To change the voltage of an alternating current
How is a voltage produced on a transformer's secondary coil?
The changing magnetic field in the core cuts across the secondary coil, inducing a voltage
The current in the primary coil conducts through the iron core and into the secondary coil
The secondary coil is attached to an external power supply
Which type of current makes a transformer work?
ac
dc
Either ac or dc
Why is a transformer core made from iron?
Iron is very dense
Iron is easily magnetised
Iron is cheap
Which of these equations correctly links potential differences and number of turns on the coils in transformers?
pd across secondary coil × pd across primary coil = no. of turns in primary coil ÷ no. of turns in secondary coil
pd across primary coil ÷ pd across secondary coil = no. of turns in secondary coil × no. of turns in primary coil
pd across primary coil ÷ pd across secondary coil = no. of turns in primary coil ÷ no. of turns in secondary coil
What kind of transformer converts 230,000 V into 11,500 V?
Step-down
Step-out
Step-up
A mains transformer (230 V) has 15,000 turns on its primary coil and 900 turns on its secondary coil. Calculate the potential difference obtained from the secondary coil (2sf).
3,800 V
14 V
140 V
A transformer has 420 turns on its primary coil. How many turns on the secondary coil are needed for it to increase the voltage by a factor of three?
140
420
1,260
What kind of transformer has 500 turns on its primary coil, and 900 on its secondary coil?
A step-up transformer
A step-in transformer
A step-down transformer
A transformer has 10 turns on its primary coil and 70,000 turns on its secondary coil. Calculate the potential difference supplied from the primary coil, if the secondary potential difference is 400 kV (400,000 V) to 2sf.
57 kV
57 V
2800 V