Electricity

Electricity

•Static •Current

Electricity occurs in 2 different forms

Current Electricity

• Moving electricity• Electrons flow through a conductor - material that allows electrons to flow through

• Circuit = continuous loop for electrons to flow

• Needs energy supply

Electrical components

•Wire•Ammeter•Battery•Fuse•Connected wires

•Bulb•Switch•Voltmeter•diode•Resistor•Rheostat

CIRCUIT TYPESThe simplest type of circuit involves electricity going around with no “choices” (electrons don’t really choose).This is called a Series circuit.

Draw the path the electrons travel-out the negative toward the positive

The other main type of circuit has two or more branches.

This is called a Parallel circuit.

Draw on the electron flow.

What sort of circuit is this?

A parallel… but, more importantly…

A short circuit.

Series circuit

• Has a single loop for electrons to travel round

• Components are connected one after another

• Current has to travel through all components

• Current is the same at all points• Voltage is shared between components

• It is either all on or all off

Series circuit

• http://www.ndt-ed.org/EducationResources/HighSchool/Electricity/seriescircuit.htm

Parallel circuit

• Has two or more paths for electrons to flow down

• Current is shared between the branches

• Sum of the current in each branch = total current

• Voltage loss is the same across all components

Practice

• http://lgfl.skoool.co.uk/keystage3.aspx?id=93

Current (I)

Current is the flow of electronsaround a circuit• DC = direct current like battery

• Electrons flow in one direction• AC = Alternating current like mains

• Electron flow changes direction 50x per second

Ammeter

• Measures CURRENT(I)• Unit = Amp (A)• Current is flow of electrons• Connect in series at the point you wish to measure

Voltage (V)

Gain or loss of energy as itpasses through a component• Voltage lost = voltage gained• In series voltage loss is shared between components

• In parallel voltage loss is the same across all components

Voltmeter

• Measures voltage• Unit = Volt (V)• Voltage increases as it passes through energy suppliers

• Voltage is decreased as it passes through users

• Connect in parallel around a component

SUMMARY

In Series In Parallel

Current

Voltage

Always the same The branches share electrons and add to the total

Voltage from source = voltage used

Voltage is shared between power users

Voltage is the same in all branches

Resistance (R)

The amount that a component slows the current

•As the electrons are slowed by a resistor, energy is lost in the form of heat.

•This means that current, resistance and voltage must be linked.

•This is Ohms law

•The unit of resistance is the ohm, symbol V

I R×

Power

Energy used by component per second

• Unit of power is the Watt, symbol is W• One watt means that 1 joule of electrical energy is being used up per second.

• Current, voltage and power are linked P

I V×

Electricity Generation

• Brainstorm ways to generate electricity

Fossil Fuels

Hydro Dam

Hydroelectric power

Nuclear power

Wind Power

Tidal Power

Geothermal

Solar

• Solar water heating• Photovoltaic cells• Solar furnace

PROBLEMS

1. Fill in the gaps in the table.

a b

c d

e f

g h

i j

k l