22 Electric fields Flashcards
electrical conductor
an object that can conduct electricity
electrically insulating materials
an electrical insulator is a material that can’t conduct electricity
gold leaf electroscope
device used to detect electric charge
electric field strength E
a point in an electric field is the force per unit charge on a small positively charged object at that point in the field
E=F/Q
(uniform field ) E=V/d
E = -V / X (change of potential between two closely spaced points at distance x apart)
E= Q/ Kr^2
electric potential V
a point in an electric field is the work done per unit charge on a small positively charged object to move it from infinity to the point in the field
V= Q / kr
coulomb’s law
for two points charge 1 and charge 2 at distance r
F=Qq / kr^2
electric current
flow of electrons from negative to positive
electrostatic charge
electrons from the outer shell of atoms can be transferred by friction
rules for forces on a test charge
treat charges as point charges
electric field lines come out radially
force between two positive test charges repel each other
electric field strength is a vector ?
true
electrons
a lepton of rest mass 9.11 10-31 and electric charge of -1.6010-19C
line of force or a field line
the direction of a line of force or a field line indicates the direction of the force. an electric field line is the path followed by a free positive test charge.
equipotential
a lien or surface in a field along which the electric or gradational potential is constant
potential gradient
at a point in a field is the change of potential per unit change of distance along the field line at that point. the potential gradient = -the field strength at any point
static electricity
like charges repel
unlike charges attract
