P13 Electromagnetism Flashcards
Rule of magnets
Like poles repel and unlike poles attract
What do the magnetic field lines of a bar magnet do
They curve around from the north pole of the bar magnet to the south pole
What is induced magnetism
Magnetism created in an unmagnetised magnetic material when the material is placed in the magnetic field.
Why is steel used in magnets and instead of what
It is used to make permanent magnets as steel doesn’t lose magnetism easily. It is used instead of iron as iron loses magnetism easily
What is a solenoid
A long coil of insulated wire wrapped around an iron bar. It is an electromagnet as it runs on electricity
What are the magnetic field lines around a wire
They are circles centred the wire. on the wire in a plane perpendicular to
What are the magnetic field lines like in a solenoid
They are parallel to its axis and are all in the same direction.
What is a uniform magnetic field
A magnetic field in which the magnetic field lines are parallel
What does increasing the current do in an electromagnet
It makes the magnetic field stronger. Reversing the direction of the current reverses the magnetic field lines
In the motor effect, why is the force increased
It is increased if the current or the strength of the magnetic field or the length of the conductor is increased
In the motor effect, why is the force reversed
The force is reversed if the direction of the current or the magnetic field is reversed.
What is an electric motor
A coil that turns when a current is passed through it.
What is magnetic flux density
A measure of the strength of a magnetic field.
