Chapter 5 - Electrostatics and Magnetism

SI unit of charge

coulomb

unit of charge

1.6 × 10^-19 C

conductors

allow the free and uniform passage of electrons when charged

insulators

resist the movement of charge and will have localized areas of charge that do not distribute

coulumb’s law

gives the magnitude of the electrostatic force vectore between 2 charges

the electric field

ratio of the force that is exerted on a test charge to the magnitude of the charge

positive test charges and negative test charges

will move in the direction of the field lines and negative charges will move opposite

electrical PE

amount of work required to bring the test charge from infinity to a given position

the electrical PE will increase when

2 like charges move toward each other or when 2 opposite charges move away from each other

electric potential

electric potential energy per unit charg

potential difference

voltage is the change in electric potential that accompanies the movement of charge from one position to another

test charges will move

spontaneously in whichever direction results in a decrease in electric PE

+ charges will move

from high to low potential

- charges will move

from low to high potential

equipotential lines

designate the set of points around a source charge

equipotential lines will always

be perpendicular to electric field line

work will be done when

a charge is moved from one equipotential line to another

no work is done when

a charge moves from points on the same equipotential line

electric dipole

2 charges of opposite sign seperated by a fixed distance

in an external EF an electric dipole will experience

a net torque until it is aligned with the electric field vector

an electric field will not

induce any translational motion in the dipole regardless of its orientation with respect tot he electric field vector

unit for magnetic field

tesla

diamagnetic materials

no unpaired electrons and are slightly repelled by a magnet

paramagnetic material

possess some unpaired electrons and become weakly magnetic in an external magnetic field

ferromagnetic material

possess some unpaired electrons and become strongly magnetic in an external magnetic field

external magnetic fields exert forces on

charges moving in any direction except parallel or antiparallel

lorentz force

sum of the electrostatic and magnetic forces in the body