Section 6 Flashcards
What do magnets affect?
Magnetic materials and other magnets.
What do both poles attract?
Magnetic materials.
What happens when magnets and magnetic material are closer together?
The stronger the induced magnetism will be.
Around a straight wire what is there?
A magnetic field.
What is the field made up of around a straight wire?
Concentric circles.
The magnetic field in the centre of a flat circular coil of wire is similar to what?
That of a bar magnet.
What are there around a coil?
Concentric ellipses of magnetic field lines.
What is the magnetic field inside a current-carrying solenoid?
Strong and uniform.
Outside the solenoid what is the field?
Similar of a bar magnet.
What is the solenoid a type of?
An electromagnet.
What is a soft magnetic material?
One which loses its induced magnetism quickly.
What is a hard magnetic material?
It keeps its magnetism permanently.
What is an example of a soft magnetic material?
Iron.
What is an example of a hard magnetic material?
Steel.
Why is iron used in transformers?
It needs to magnetise and demagnetise.
How can you increase the strength of a magnetic field around a solenoid?
Add a soft iron core.
Why does a wire move?
Charged particles moving through a magnetic field will experience a force, as long as they’re not moving parallel to the field.
What do transformers do?
Change the size of the voltage of an alternating current.
What coils are on a transformer and what are they joined by?
Primary and secondary joined with an iron core.
What happens when an a.c voltage is applied across the primary coil?
The magnetically soft iron core magnetises and demagnetises quickly. This induces an a.c voltage in the secondary coil.
What do step up transformers do?
They have more turns on the secondary coil than the primary coil.
What a step down transformer?
Steps the voltage down. They have more turns on the primary coil than the secondary.
Vp / Vs =
Np / Ns
Vp x Ip
Vs x Is
What is the problem with the voltage produced by power stations?
It is too low to be transmitted efficiently.
What is used to boost the voltage before it is transmitted?
A step up transformer.
Why is a stepdown transformer used at the end of the journey?
To reduce the voltage so it is more useful and safer to use.
