Electricity

Electricity Electrical energy produced when electric current flows. A source of electrical energy is any device that produced electrical energy.

Sources of electrical energy Chemical cell Biomass fuel Solar cell Geothermal energy Hydroelectric power Wind energy Tidal energy Fossil fuel Nuclear energy

Electric current 2 types of electricity : a) electrical charges (electrostatic) b) electrical current Electric current is produced when there is a flow of negative charges

Electric current : from positive to negative Electron : from negative to positive

Electric Current Rate of flow of negative charges in a circuit Unit : ampere (A) Measuring device : ammeter To measure current, ammeter must be connected in series, in a circuit.

Voltage The force that is needed to make charges flow from one point to another in a conductor Unit : voltage (V) Measuring device : voltmeter To measure voltage, voltmeter must be connected in parallel, in a circuit.

Resistance The property of a substances that opposes the flow of electric current A substance with very high resistance only allows a small current to flow through it. Unit : ohm ()

Resistance Depends on :a) diameter/ thickness of conductor Big , small b) length of conductor long , short c) type of conductor tungsten , copper

Symbols

Voltage, current and resistance in a series circuit Total current I = I1 = I2 = I3 Total voltage V = V1 + V2 + V3 Total resistance

Series circuit

Series circuit

Series circuit

Voltage, current and resistance in a parallel circuit Total current I = I1 + I2 + I3 Total voltage V = V1 = V2 = V3 Total resistance 1/R = 1/R + 1/R + 1/R

Parallel circuit

Parallel circuit

Parallel circuit

The differences