Unit for current: ampere
--> represents 6.24 x 1018 electrons passing some point per second
Unit for electric charge: coulomb
--> the quantity of electric charge which passes some point when a current of 1 ampere flows for a period of one second.
* equivalent to 6.24 x 1018 electrons
Unit for voltage: volt
--> the potential difference which produces a current of 1 ampere in a substance where the rate of energy dissipation is 1 watt.
Unit for resistance: ohm
--> the resistance which will allow 1 ampere of current to flow under the influence of a potential difference of 1 volt.
A measure of the ability of an object to hold electrical charge
Unit for capacitance: farad
--> the capacitance of an object for which the electrical potential increases by 1 volt when one coulomb of charge is added to it.
Charge = Voltage x Capacitance
Stored energy
= 1/2 Charge x Voltage
= 1/2 Capacitance x Voltage^2
Voltage = Resistance x Current
(cf: pressure = flow x resistance)
Impedance - resistance that is dependent on frequency of the alternating current.
* symbol Z
* unit: ohm
About | |
Created | 20050601 |
Reviewed | 20050601 |