Transformers Flashcards
What does a transformer change?
The voltage of an alternating current
What is a transformer made up of?
Two insulated coils wound around a soft iron core to enhance the magnetic field strength
How does a transformer work?
The alternating current in the primary coil produces an alternating magnetic field, which induces an alternating current in the secondary coil. They use electromagnetic induction to change the voltage in a circuit.
What are the features of a step-up transformer?
More turns on the secondary coil, increases voltage
What are the features of a step-down transformer?
More turns on the primary coil, decreases voltage
In a power station, a generator produces electricity at how many volts, has a power output of how many mega-watts and produces a current of how many amps?
20,000V, 500MW, 20,000A
What voltage does a step-up increase voltage to?
400,000V
How is power lost in power lines?
Resistance in the wires causes a heating effect. This increases as the current increases
What voltage does a step-down decrease voltage to for factories?
33,000V
What voltage does a step-down decrease voltage to for homes?
230V
Why are transformers almost 100% efficient?
All the power supplied to the primary coil is delivered to the secondary coil, and then to the device
How do you work out the 100% efficiency?
Ip X Vp = Is X Vs
What is the transformers ratio?
Vs / Vp = Ns / Np
How do you work out the number of coils on the primary coil?
Ns / (Vs / Vp)
How do you work out the number of coils on the secondary coil?
Np X (Vs / Vp)
