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Transformers use electromagnetic induction to change the voltage of alternating currents. The voltage and current changes can be calculated, as the power transfer is constant.
What is the function of a transformer? - Higher
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? - Higher
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? - Higher
Either ac or dc
Why is a transformer core made from iron? - Higher
Iron is very dense
Iron is easily magnetised
Iron is cheap
Which of these is the correct equation for calculating electrical power?
Power (J) = current (A) × potential difference (V)
Power (W) = current (A) × potential difference (V)
Power (J) = current (A) ÷ potential difference (V)
Which of these equations correctly links potential differences and number of turns on the coils in transformers? - Higher
What kind of transformer converts 230,000 V into 11,500 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? - Higher
A transformer converts 460 V into 230 V. The power output is 2.3 kW, how much current is drawn into the primary coil?
Why do National Grid overhead transmission cables use very high voltages?
Higher voltages mean higher currents which wastes less energy
Higher voltages mean lower currents which wastes more energy
Higher voltages mean lower currents which wastes less energy