17 Voltage is the potential difference between two points in a circuit. Voltage is the potential energy that makes the electrical current flow in a circuit by pushing the electrons around.
18 Symbol of voltage in formula: V Units: voltsSymbol of volts: V
19 VoltageA measure of how much work is needed to move a charge between two points.The size of the current depends on the voltage. If the voltage between two points on a wire is increased, more current will flow in the wire.
26 Conductors and insulators A conductor in electricity is a material that allows electrons to flow through it easily. Metals, in general, are good conductors.An insulator is a material that is a poor conductor of electricity. Examples include plastic, wood, ceramic and glass.
27 Symbol of conductance in formula: G Units: SiemensSymbol of ohms: STo calculate conductance in terms of Resistance, we use this formula:R= 1/G G= 1/R
30 ExercisesWhat current flows between a potential difference of 120 V through a resistance of 30 Ω?A motor with an operating resistance of 30 Ω is connected to a voltage source. 4.0 A of current flow in the circuit. What is the voltage of the source?If the conductance of a circuit is 0.25 S, and the current is 2.0 A, what is the overall voltage?An ammeter measures current. What will the ammeter read when it is connected to a 90 V source and a 60 Ω resistor?
33 Electrical PowerThe rate at which electrical energy is changed into other forms of energy. The watt tells how quickly a device (e.g. bulb) uses electrical energy.Symbol of power in formula: PUnits: watts (Joules/s)Symbol of watts: WPower= voltage x current