What is an electric current
a flow of charge carriers
Charge formula
Q=It (quit)
What is electron density (n)
number of electrons per unit volme
high in copper
Long current formula
I=Anve
current=cross-sectional areaelectron densityvelocity (drift) of electronselectronic charge (1.610^19)
Resistance formula
resistance = voltage / current
V=IR
Potential difference definition
energy transferred per unit charge
Electro Motive Force definition
the amount of electrical energy gained by a coulomb of charge to go round in the electrical circuit
Power formula
P=VI
Power is Very Important
Ohm’s law
the current in an electrical conductor is directly proportional to the amount of potential difference maintained across it
Resistivity formula
RolAR
resistivitylength = cross-sectional arearesistance
resistance = resistivity*length/cross-sectional area
Relationship with light for Light-Dependent Resistor (LDR)
as light intensity increases, resistance decreases
Relationship with temperature for thermistor
as temperature increases, resistance decreases
