Magnetism and electromagnetism NOT ALL Flashcards
PMT summary notes up until motor effect
1
Q
permanent magnets
A
always magneticc, always have poles
2
Q
induced magnets
A
- magnetic but no fixed poles
- can be made into temporary magnets by rubbing against a permenant magnet
3
Q
what happens when you turn induced magnets into temporary magnets
A
- rubbing an induced magnet against a permanent magnetic aligns the domains in the material in all the same direction
- creating a temporary magnet
4
Q
what are domains?
A
a region of a magnetic material in which the magnetic fields of the atoms are all aligned in the same direction. This alignment creates a strong magnetic field within the domain.
5
Q
what are induced magnets made of
A
iron nickel cobalt
6
Q
field lines pointy from… to…
A
from north to south
7
Q
strength decreases with.. from the magnet
A
distance
8
Q
plotting compasses
A
mini compasses for drawing
9
Q
Earth’s core
A
- core is magnetic
- creates large magnetic field around the earth
- we know this because a magnetic compass will align itself with the earth’s field lines and point north
- earth’s north and south poles are actually switched
10
Q
Current
A
- produces a magnetic field around the wire
- direction can be found using ‘right hand grip rule’
- increasing current increases strength of magnetic field
11
Q
solenoid
A
- coiled wire
- coiling the wire causes the field to align and form a giant single field, instead of lots of small ones, this enhances the magnetic effect
- having an iron core increases its strength because it is easier for magnetic field lines to pass through than air is
- factors that affect strength: size of current, lenght, cross sectional area, number of coils, using a soft iron core
12
Q
motor effect
A
- when a magnet and wire’s magnetic fields interact with each other
- makes a straight magnetic field (instead of circular)
- wire is pushed away from the field between the poles
13
Q
fleming’s left hand rule
A
FBI
force, magnetic field, current
14
Q
FBI equation
A
F=BIL
force = magnetic flux density x current x length
15
Q
units:
magnetic flux density
A
tesla, T
