P3 - Transformers Flashcards
What do both types of transformer have? [2].
Two coils: the primary and secondary, joined with an iron core.
What do step-up transformers do and how?
Step the voltage up. They have more turns on the secondary coil than the primary coil.
What do step-up transformers do and how?
They down step the voltage down. They have more turns on the primary coil than the secondary coil.
How do transformers work?
A magnetic field is produced by the primary and transferred to the secondary.
What type of current is in the primary coil? What does this mean?
AC.
The field is changing direction/it is a changing magnetic field.
What does the relative number of turns on the two coils of a transformer determine?
Whether the PD induced in the secondary coil is great or less than in the first.
In a step-up transformer, the PD across the secondary coil is ____ than the PD across the first coil.
Greater.
In a step-down transformer, the PD across the secondary coil is ____ than the PD across the first coil.
Less.
What would happen if you supplied DC to a transformer and why?
No induction in the secondary because you need a changing field to induce a PD.
What does the iron core of a transformer do?
Transfers the changing magnetic field. No electricity flows through it.
Name two different types of transformer.
Step-up and step-down.
What is the formula for PD or turns in transformers?
PD in 1st / PD in 2nd = No turns 1st / no turns 2nd
Transformers are nearly 100% efficient so..
Power in = power out.
What is the formula for power supplied in a transformer?
P = I x V.
What are switch mode transformers?
Transformers that operate at high frequencies than traditional ones.
