Magnetism and electromagnetism Flashcards
What is an induced magnet?
It is an object that BECOMES a magnet when it is placed in a MAGNETIC FIELD.
What is a permanent magnet?
A magnet that produces its OWN MAGNETIC FIELD.
Name 4 types of magnetic material.
- iron
- steel
- cobalt
- nickel
(These can be made into a PERMANENT MAGNET or an INDUCED MAGNET).
Where is the magnetic field strongest in a magnet?
At the POLES.
How can the direction of a magnetic field be found?
Using a COMPASS.
How can u plot the magnetic field of a magnet? [6]
- Place the COMPASS near the NORTH pole of the bar magnet. - Then draw a CROSS at the NORTH pole of the compass. - MOVE THE COMPASS so the SOUTH pole of the compass is ON THE CROSS. - Again draw another CROSS at the NORTH pole - Continue until plotted a complete MAGNETIC FIELD LINE.
What direction does the magnetic field line always run from?
The NORTH POLE to the SOUTH POLE.
What causes the Earth’s magnetic field?
The movement of liquid, magnetic iron in the Earth’s core.
What happens when a current flows through a conducting wire?
A MAGNETIC FIELD is produced around the wire.
What is a solenoid?
A COIL OF WIRE used to increase the strength of the magnetic field.
What 3 ways are there to increase the magnetic field produced by a solenoid?
- Increasing the CURRENT. - Increasing the number of COILS of the WIRE. - Place a piece of IRON inside the solenoid (IRON CORE).
What is a solenoid containing an iron core called?
An ELECTROMAGNET.
What 2 key uses are there of electromagnets?
- Can CHANGE the strength of the MAGNETIC FIELD.
- Can be turned ON and OFF.
What is meant by the motor effect?
When a wire carrying an electric current is placed into a magnetic field and experiences a FORCE.
What is meant by the magnetic flux density?
It is a measure of the STRENGTH of the magnetic field.
How would you determine the direction of the force? (carrying on from motor effect)
Using Fleming’s left hand rule.
What does your thumb, first and second finger represent in Fleming’s left hand rule?
- Thumb - motion (the FORCE)
- First finger - magnetic field (N to S).
- Second finger - current (+ to -).
What will happen to the conductor when it is parallel to the magnetic field? (carrying on from motor effect)
It will NOT EXPERIENCE A FORCE.
Name 1 important use of the motor effect.
Electric motors.
What device do we use to switch the direction of the current when the loop passes 90°? (electric motor)
SPLIT-RING COMMUTATOR.
What does the split-ring commutator do and what does this allow the motor to do?
Switches the DIRECTION OF THE CURRENT to KEEP ROTATING IN THE SAME DIRECTION.
