What is the function of a transformer?
To transfer magnetic fields
To connect separate circuits together
To change the size of 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?
A.C.
D. C.
U. V.
Why is a transformer core made from iron?
Iron is very dense
Iron is easily magnetised
Iron is easily made into a permanent magnet
Which of these equations correctly links potential differences and number of turns on the coils in transformers?
\[\frac{V_{s}}{V_{p}}=\frac{N_{p}}{N_{s}}\]
\[\frac{V_{s}}{V_{p}}=\frac{N_{s}}{N_{p}}\]
Vs x N s = Vp X Np
What kind of transformer converts 230,000 V into 11,500 V?
Step-down transformer
Step-out transformer
Step-up transformer
A transformer has 420 turns on its primary coil. How many turns are on the secondary coil if it steps up voltage from 100 V to 300 V?
140
420
1260
Why do National Grid overhead transmission cables use very high voltages?
Stepping up voltage means stepping up current, which wastes less energy.
Stepping up voltage means stepping up current, which wastes more energy
Stepping up voltage means stepping down current, which wastes less energy
What type of transformer is used close to domestic consumers to return voltage from the Grid to 230 V, for safe use in the home?
A transformer converts 460 V into 230 V. The power output is 2.3 kW, how much current is drawn into the primary coil?
4.6 A
5.0 A
1.15 A