electromagnetism Flashcards
coulombs law
magnitude of the electrostatic force of attraction or repulsion between two point charges is directly proportional to the product of the magnitudes of charges and inversely proportional to the square of the distance between them
coulombs law equation
F=Q1Q2/4πε0r^2
is force vector or scalar
vector
what is an electric field
is the region that surrounds electrically charged particles in which a force is exerted on other electrically charged particles.
where does charge reside in a conductor
the outer surface
what is the electrical field inside a conductor
0
electrostatic shielding
when a conductive material is used to enclose a device that is effected by an electric field
electrical force per unit POSITIVE charge
electric field charge
the force that a positive +1C would experience if placed in an electric field
electric field strength
electric field strength equation
E=F/Q
electric field strength units
newtons per coulomb
two uses of the inverse square law
electric field strength and the gravitational field
where is the charge concentrated in an electric field
the centre
electric field strength equation
E=Q/4πε0r^2
what is electric field strength measured in
newtons per coulomb
is electric field scalar of vector
vector
explain the electric field strength graph
electric field strength is 0 until radius is reached on x axis
a sudden slope downwards from radius point
what is the electric field strength inside the sphere
0
what is the electric field strength outside the sphere
Equal to point charge Q in the centre of the sphere
electrical potential definition
the work done in moving unit positive charge from infinity to that point
the radial field
the electrical potential at a distance from a point charge
what is electrical potential measured in
V or jules per coulomb
describe the electrical potential graph
electrical potential is at its highest until radius is reached
graph slopes off less steep
change in electrical potential energy
work done
applications of electrostatic defelections
deflection experiments to measure the charge to mass ratio for the electron
what is the potential difference definition
the work done in moving one coulomb
of charge from one point to the other against the electric field,
what is milikans oil drop experiment used for
to determine the size of the charge of an electron
what is an electron volt
a unit of energy, often used in high-energy particle physics.
electron volt definition
the energy acquired when one electron accelerates through a potential difference of one volt.
value of one electron volt
1.6x10-19
ferromagnetic materials
materials which can become permanently magnetised
common materials of ferromagnetic materials
iron steel cobalt and nickel
what are magnetic dipoles
the tiny magnetic effects outer shell electrons cause.
how are magnetic dipoles usually aligned
in domains that are random and cancel each other out
what happens when a ferromagnetic material is placed within a magnetic or electromagnetic field
the material is magnetised
what happens when a ferromagnetic material is magnetised
the magnetic dipoles align themselves with the magnetic field they are in creating a strong uniform magnetic field.
how can a bar magnet be demagnetised
heating up
how can a ferromagnetic create a permanent magnetic field
by heating the cooling fully
how can a magnet lose its magnetism other than being heated up
mechanical shock
what is a magnetic field
a region of space round a magnet where another magnet will experience a force
what does the relative spacing of feld lines around a magnet show
the fields strength
what direction do the field lines travel
north to south
what happens when a current flows through a wire
a circular magnetic field is produced
(left hand rule)
what happens when current flows through a coiled wire
create a magnetic field like the bar magnet
what happens in the middle of a solenoid
an almost uniform magnetic field
how can the magnetic field of a solenoid be increased
wrapping it round an iron core
increasing number of coils
what is the direction of magnetic field dependant on in a solenoid
direction of current flow
what would happen to earth wihtout a magnetic field
atmosphere would be stripped away by solar wind
magnetic induction (B)
the strength of a magnetic field at a point
equation for magnetic induction
B=μ₀I/2πr
what is magnetic induction (B) measured in
tesla
what is one tesla
the magnetic induction of a magnetic field in which a conductor of length one METER carrying a current of one AMPERE PERPENDICULAR to to the field is acted on by one newton of FORCE
how can magnetic induction be measured
hall probe
search coil
force on a current carrying wire in a magnetic field equation
F=IlBsinθ
movement of a charged particle in a magnetic field
F=qvB
what path does a charged particle take in a magnetic field
circular
centrepedal acceleration equation
a=v^2/r
centripedal force equation
F=mv^2/r
radius of path equation
r=mv/qB
what happens when a particle enters a field at an angle
will follow a helical path
what is the pitch
the distance between adjacent loops in the helix after on period
pitch equation
P=vcosθT
frequency of rotation equation
f=qB/2πm
what is orbit frequency NOT based on
speed or radius
what is orbit radius based on
charge to mass ratio
magnetic induction
why is kinetic energy constant
orbital speed is constant
