Electricity Flashcards
Quantised charge of charge carriers?
Protons: 1.60 x 10^-19
Electrons: 1.60 x 10^-19
Formula for charge
Q=It
Formula for Current in current carrying conductor
I = Anvq
A = cross sectional area (m^2)
n = number density (m^-3)
v = avrg drift speed of charge carriers flowing per second (ms^-1)
q = quantised charge of charge carrier (1.60x10^-19)
Define potential difference
And cause of pd
definition: it’s the energy transferred per unit of charge
cause: cells causes the ends of the circuit to be positive on one end and negative at the other
Formula for potential difference according to it’s definition
V = W/Q
W = work done (J)
p.d is the energy transferred per unit charge
energy transferred is the same as work done (J)
Formula for electric power?
P = IV
P = watts (W)
variation w resistance
1. P=I^2R
2. P = V^2/R
Twinkle twinkle little star power equals I squared R
Current in series vs parallel
Series
I = I
–> same across all components
Parallel
I = I+ I
Voltage in series vs parallel
Series
V = V + V
Parallel
V = V
opposite of current
Resistance in series vs Parallel
Series
R = R + R
Parallel
1/R = 1/R + 1/R
Define Resistance
Opposition to current
Formula of Resistance
R = V/I
R = Ohms
What does the Ohm’s Law state
and what’s the formula?
For a conductor at a constant temperature, the current that passes through it is proportional to the potential difference across it.
Pokoknya it states that electric current is proportional to voltage and inversely proportional to resistance, hence the formula I = V/R
which can be written as V = IR
Formula of Resistivity
R = pL/A
p = resitivity (ohm meters)
L = lengh of wite (m)
A = corss sectional area of wire (m^^2)
Describes how material opposes the flow of electrons (because of the ions in the material the electrons movement is affected)
Resistance in LDR
As the light decreases the resistance increases
box w 2 arrows
Resistance Thermistor
As temperature decreases, the resistance increases
