electric circuits topic 3 Flashcards
I =
Q/t
current =
rate of flow of charge
V =
W/Q
potential difference =
work done per unit charge
PD cross components in parallel is
the same
what are charge carriers in a circuit
free electrons or conduction electrons
current in terms of drift velocity
nqvA
R =
V/I
Area of a wire
pi r^2
R = (resistivity)
pl/A
for an ohmic conductor
R is a constant
conditions for the graph of an ohmic conductor
-passes through origin
- straight line
IV graph of a metallic conductor
straight line
IV graph of a filament lamp
s curve
resistivity of a metal increases with
temperature
why does heating a metal make it harder for electrons to move
the lattice of ions vibrates more, so more collisions occur
what happens to current when temperature increases
current decreases and resistance increases
what happens to resistance as temp increases in an NTC
resistance decreases
IV graph of an NTC thermistor
upwards curve
What happens to current if the intensity of of light on an LDR increases
current increases so resistance decreases
diodes only let current flow
in one direction
P =
VI
other power equation
=V^2/R and = I^2R
E=
VIt
what is internal resistance
electrons collide with atoms causing resistance in a battery
what is emf
total amount of work the battery does on each coloumb of charge
energy wasted per coloumb overcoming the internal resistance is called
lost volts
emf =
W/Q
emf also =
V + Ir
total emf in series =
e1+e2…
total emf in parallel =
e1=e2=e3…
V = emf -
v
