Magnetic Fields Flashcards
What must charged particles be doing for a magnetic field to be produced?
They must be moving
Ferromagnetism
Magnetic fields of atoms line up in parallel to each other called in areas called magnetic domains.
Examples Iron, Nickel, Cobalt
Convention for magnetic field lines
Direction from north to south, distance between lines increase further away from magnet.
Why is geographic north at actual South Pole of Earths magnetic field
Flow of liquid iron within the earths core which produces electric current, flow over time changes direction so poles are currently opposite to their geographic counterparts.
Left hand grip for electron current
Thumb: points in direction of electron flow.
Fingers: Field lines
Unit and symbol of magnetic field strength
Symbol:B
Unit: T
1 Tesla (T) is equal to
1NA^-1m^-1
Force acting on straight wire at any angle to straight line magnetic field
F=BIlsinØ
Where F is force acting on wire (N)
B is magnetic field strength (T)
I is current (A)
l is length of wire in field (m)
And Ø is angle wire makes with magnetic field (°)
Force acting on straight wire perpendicular to magnetic field
F =BIl
Since sin90° =1
Right hand rule
For negatively charged particles
Centre finger :Current
Forefinger: magnetic Field direction
Thumb: Thrust, direction of force on charged particle
Magnitude of magnetic field strength, B, equation
B =uoI/2pir
B is magnetic field strength (T)
uo is permeability of free space: 4pi*10^-7 TmA^-1
I is current in A
r is radius (m)
velocity and magnetic field strength equation
F =qvB
Where F is force acting on charged particle (N)
q is charge of charged particle (C)
v is velocity (ms^-1)
B is magnetic field strength (T)
Explanation of helical motion
Charged particle has both circular and linear motion in the magnetic field.
Circular motion due to the component of its velocity perpendicular to the field (vsinx°)
Linear motion due to component of its velocity parallel to the magnetic field (vcosx°)
Plasma
Fourth state of matter, when electrons have detached from atoms leaving a cloud of ions
