Magnetism & Magnetic Fields P4 Flashcards
(20 cards)
What is the law of magnetism?
two like poles repel eachother and two unlike poles attract eachother
What type of force is the attraction/repulsion between two magnetic poles?
Non-contact force
3 examples of magnetic metals
1 iron
2 cobalt
3 nickel
What are the two types of magnets?
induced and permanent magnet
What do permanent magnets produce?
it’s own magnetic field
What is an induced magnet?
when a magnetic material becomes a magnet in a magnetic field
What is a magnetic field?
the region around a magnet where a force is exerted on another magnetic material
What are magnetic field lines used for?
to show the strength and direction of a magnetic field
what should the direction of the magnetic field lines be?
north to south
What is a uniform magnetic field?
the gap between opposite poles
What direction does the magnetic compass on earth point to?
geographic north pole
what is the right hand thumb rule?
the thumb points in the direction of the current and the other fingers give the direction of the field
what are the factors that affect magnetic field strength?
1 the size of the current
2 the distance of wire
What happens if no current flows through a wire?
no magnetic field
3 ways of increasing the strength of an electromagnet
1 increase the current
2 increase the number of coils
3 add an iron core
when does the motor effect occur?
when a wire with current flowing through it is placed in a magnetic field and experiences force
how to increase the size of the force exerted by the magnetic field
1 increase the current
2 use stronger magnets
3 placing wires 90 degrees to the direction of magnetic field lines
calculation for magnetic force on a current carrying conductor
force = magnetic flux density x current x length
what is flemings left hand rule?
used to see the direction of a force on a current carrying wire. the thumb is force, index finger is magnetic field, the middle finger is current
what are factors that affect the direct current motor?
the speed - increasing current, use a stronger magnet
direction of rotation - reversing current supply and poles
