Magnetism and Electromagnetism Flashcards
1
Q
Law of magnetism
A
- two poles: north and south
- two like poles repel each other
- two unlike poles attract each other
- magnetism can be induced in some materials by placing them in a magnetic field
2
Q
properties of magnetically hard and soft materials
A
HARD:
- difficult to magnetise
- do not easily lose their magnetism (permanently magnetised)
- e.g. steel
SOFT:
- easy to magnetise
- easily lose their magnetism (temporarily magnetised)
- e.g. iron
3
Q
Magnetic field
A
- the region around a magnet where a force acts on another magnet or on a magnetic material
- strongest at the poles
4
Q
magnetic field lines
A
- used to represent the strength and direction of a magnetic field
- direction is shown using arrows
- strength is shown by the spacing of the magnetic field lines
- if magnetic field lines are close together the magnetic field is strong
- if the magnetic field lines are far apart the magnetic field is weak
5
Q
rules for magnetic field lines
A
- always go from north to south
- must never touch or overlap other field lines
6
Q
investigation of magnetic field pattern for a permanent bar magnet (1)
A
- put magnet under a piece of paper
- sprinkle iron filings on top
- tap paper until iron filings form a clear pattern
7
Q
investigation of a magnetic field for a permanent bar magnet (2)
A
- use multiple compasses to see the magnetic field lines coming out of a bar magnet
8
Q
two permanent magnets producing a uniform magnetic field
A
- point opposite poles of the two magnets a few centimetres apart
- a uniform magnetic field will be produced in the gaps between opposite poles
9
Q
electric current in a conductor
A
- produces a magnetic field around it
- the larger the electric current, the stronger the magnetic field
- the direction of the magnetic field depends on the direction of the current
10
Q
electromagnets
A
- a coil of wire rapped around a magnetically soft core
- can be turned on and off
11
Q
factors affecting strength of magnetic field
A
- more Current
- more loops (number of Coils)
- inserting an iron Core
12
Q
The motor effect
A
- occurs when a current-carrying wire is put between magnetic poles
- the two magnetic fields affect one another
- this can cause the wire to move
13
Q
the motor effect (2)
A
- this is because charged particles moving through a magnetic field will experience a force, as long as they’re not moving parallel to the field lines
14
Q
the motor effect (3)
A
- can be used to create a simple d.c. electric motor
- a simple d.c. electric motor consists of a coil of wire positioned in a uniformed magnetic field
