Electricity Flashcards
what is emf
electromotive force
what is emf measured in
volts
definition of current
rate of the flow of charge in a circuit or component
what is the smallest possible charge (electron charge)?
1.6x10-19
what values must charge be
0 or multiple of the electromotive force
steps of induced charge given a wall and a balloon rubbed against your head
-balloon becomes negatively charged
-balloon put against wall and like charges repel so electrons repelled to other side of the wall
-opposite charges attract so balloon ‘sticks’ to wall
what is direction of conventional current flow
positive to negative
what causes a spark
large build up of charge, large p.d. between object and earth causes electrons to jump between gap and cause a spark
rule of current in series
I=I=I
rule of p.d. in series
V=V+V
rule of resistance in series
R=R+R
rule of current in parallel
I=I+I
rule of p.d. in parallel
V=V=V
what happens to resistance if more resistance is added in parallel
resistance of whole circuit decreases as there are more paths for current to flow
definition of emf
amount of energy transferred to electrical energy
definition of potential difference
amount of energy transferred from electrical to other stores
what is an electronvolt
amount of energy an electron gains by passing through 1V
what is the value of 1eV
1.6x10-19J
what is ohms law
electrical current through a conductor is directly proportional to p.d. and inversely proportional to resistance
what is definition of resistance
the opposition to current
what is definition of resistivity
fundamental property of a material that measures how strongly it resists electrical current
does resistance or resistivity change with length, area
resistance!
what is rho
resistivity
what is l
length (of wire)
