23 - Magnetic Fields Flashcards
ways to draw magnet’s magnetic field
dump iron filings or use a plotting compass with a bar magnet
direction of magnetic field lines are always
north to south
direction of earth’s magnetic field
south pole towards north pole (geographically) therefore bar magnet would have north pole and geographic south pole
define magnetic field
the region around a permanent or magnet or a current carrying conductor in which other magnetic objects will experience a force
what is the current carrying conductor responsible for the earth’s magnetic field
the earth’s molten core
where is magnetic field strongest around a magnet and why
at poles due to field lines being closest
what is responsible for creating a magnetic field around a bar magnet
the flowing of free electrons
electromagnetism
when a charges particle moves, it creates a magnetic field so when a current passes through a wire, a magnetic field is produced.
how to find direction of magnetic field around current carrying wire
using right hand grip rule (thumb is current, rest is field direction)
when representing in exam, make sure each field line gets further away from each other from the wire
magnetic field of solenoid is
uniform in the middle
how to find direction of field for solenoid
use right hand grip rule but thumb is field direction and rest are current direction
north and south poles for solenoid
the solenoid produce north and south poles at their opposite faces
how to determine direction of force on current carrying conductor in external magnetic field
Fleming’s left hand rule
force on current carrying wire
F=BILsinϑ
force = magfluxdensity x current x length x sinϑ
ϑ is the angle betwee FIELD and CURRENT
if perpendicular F=BIL
if parallel F=0
what is magnetic flux density
the strength of the magnetic field measured in Tesla T
what is one tesla equal to
the magnetic flux density when a wire of length 1m carrying a current of 1A is perpendicular to the field, experiences a force of 1N
other equations relating to magnetic fields that can be used in qs where factors increase and decrease
R=pL/A and V=IR - V is constant
how are northern lights created
charged particles from the sun spiral down the Earth’s magnetic field to the poles (strongest), colliding with atoms in the atmosphere to emit light
electron flow and flemings left hand rule
electron flow is opposite to conventional current - important in flemings left hand rule
force on electric charge in magnetic field
F=Bqvsinϑ
force = magfluxdensity = charge x velocity x sinϑ
F=Bqv if perpendicular
motion of elec charge in magnetic field
circular motion
radius of circular motion equation and derived
F=mv2/r and F=BQv
cancel out v so
r=mv/BQ
electron motion around field lines - radius of circular motion
electrons spiral around field lines due to constant component velocity in direction of field lines
velocity selector
a device that uses both electric and magnetic fields to select charged particles of specific velocity
Forcemagnetic = Forceelectric
BQV=EQ
so V=E/B
