Current and Charge
Current is the rate of flow of charge.
Charge is energy stored chemically, for conversion into electricity.
-Current is measured in Amps.
-Charge is measured in Coulombs.
-The formula relating current and charge is I = delta Q / delta T
-In a metal, electrons are the charge carriers. Their charge is 1.602 x 10 -19
-As well as electrons, ions in fluids can also be the charge carriers.
The formula relating current, time and charge = I = delta Q / delta T
The formula relating power, current and p.d = P = I x V
The formula relating resistance, current and p.d = R = V / I
Potential Difference is the energy provided or used per unit charge.
-Potential difference is measured in volts.
-The voltage supplied to a circuit by a power pack/cell is called EMF (electric motive force).
-The total EMF is equal to the total P.D
-Formula for power is P = I x V
Resistance is a materials opposition to the flow of electric current.
-Resistance is measured in Ohms.
-The formula for resistance is R = V / I. This is Ohms law, it implies that resistance is constant for a particular material.
-Factors that effect resistance include temperature,
Resistivity is to do with the resistance of a certain material.
The unit of Resistivity is