P15 - Electromagnetism Flashcards
Like poles?
Unlike poles?
Like poles repel
Unlike poles attract
Any iron or steel object?
Can be magnetised or demagnetised
Region around magnet?
Magnetic field
Magnetic field lines?
Lines of force
Line of force direction?
Always n-s pole
Induced magnetism?
Placing an unmagnetised magnetic material in a magnetic field
Iron and steel are what type of magnet?
Permanent magnet
Solenoid?
A long insulated coil of wire
Shape of magnetic field lines in solenoid?
Each is a complete loop
Electromagnet?
A solenoid where insulated wire is wrapped around iron bar
Reversing the current…
Reverses the magnetic field lines
Uniform magnetic field?
one in which the magnetic field lines are parallel
Magnetic field lines around a wire?
circles centred on the wire in plane perpendicular to the wire
E. Magnetic flux density?
force = megetic flux density x current x length (N) = (T, tesla) x (I) x (M)
D. Motor effect?
When a current is passed along a wire in a magnetic field, and the wire is not parallel to the lines of the magnetic field, a force is exerted on the wire by the magnetic field
D. Magnetic flux density?
the measure of the strength of a magnetic field - (B is the symbol and is measured in teslas, T)
Flemming’s left hand rule?
a rule that gives the direction of the force on a current-carrying wire in a magnetic field according ti the directions of current and field
D. Split ring commutator?
Metal contacts on the coil of a direct current motor that connects the rotating coil continuously to its electrical power supply
Why does the coil spin when current is passed through it?
- a force acts on each side due to the motor effect
- `the force on one side is in the opposite direction of the force on the other side
