11. Electricity: Electric Circuits Flashcards
what is current
flow of charge through a electrical circuit
what is current measured in
amperes (A)
what is the equation for current
I = Q/t
I = current
Q = amount of charge
t = time
how do e- move in an electrical circuit
e- move towards the positive connection
e- removed at the + connection while more e- are entering the circuit at the - connection
why does e- movement occur in a circuit
because there are 2 points of the circuit that have a significant potential difference
what is ohms law
state that the voltage can be determined by multiplying the current by resistance
what is ohms law equation
V = IR
v= voltage
I = current
R = resistance
what is resistance
measure of hindrance of e- flow
what is resistance measured in
ohms
what is resistivity
measure of materials tendency to resist e- flow
what is the relationship between temperature and resistivity
increase temp = increase resisitivity
what is the resistance equation
R = pl/A
p = resistivity (ohm x m)
l = length of wire (m)
A = cross section area of wire (m^2)
what is an in series circuit
components lined up in a row along the wire, only one path for e- to flow
what is the voltage like at diff points in the in series circuit
same over each component
what is the equation for resistance in series
Rt = R1 + R2 + R3…
what is parallel circuit
components are in alternate paths and there is more than one path for e- to flow
what is the total current in parallel circuits
total current = sum of currents for each path
what is the voltage for all paths in paralell
voltage is the same throughout the circuit for all paths in parallel
what is the equation for resistance in parallel
1/Rt = 1/R1 + 1/R2 + 1/R3 …
what does a battery do
add energy to circuit by raising voltage from one point to another
what is the electromotive force
energy added by a battery
what is the unit of emf
volts
if 2 batteries are connected in opposition (positive end to positive end) what will happen to the energy
energy will be lost from the charge when passing through the second battery
what is the first law of kirchhoff
amount of current flowing into any node must be the same amount that flows out
all current arriving at a node is defined as positive and all current leaving is -
what is a node
intersection of wires
what is kirchhoffs second law
sum of voltages around any path in a circuit must equal to 0
what is the function of a capacitor
temporarily store energy in a circuit
what is energy stored as in capacitors
in the form of separated charge
what are dielectrics
material that increases capacitance
what is capacitance
ability to store charge per unit volume
what is the equation for capacitance
C = Q/V
Q = charge (Coulomb)
what is capacitance in terms of # of coulombs
of coulombs needed to raise the potential of a conductor by one volt
what does the separation of charge in a charge parallel plate capacitor create
creates constant electric field
what is the equation for voltage and capacitors
V = Ed
E = electric field strength
d = distance between plates of capacitors
what is the equation for total capacitance in a series circuit
1/Ct = 1/C1 + 1/C2 + 1/C3…
what is the equation for total capacitance in a parallel circuit
Ct = C1 + C2 + C3…
what is electric power
represents rate at which energy is converted from electrical energy of moving charges into another form of energy
what are the 3 equations for power
P = IV
P = I^2R
P = V^2/R
increase in area of plates in a charged parallel plate capacitor will have what effect on capacitance
increase
increase in distance between the 2 plates in a charged parallel plate capacitor will have what effect on capacitance
decrease
