TERM 4

Unit 1: Electrical Systems

1.1 Simple circuit components In every system an electrical circuit has

three components Input Process Output

Can you think of examples of each?

Unit 1: Electrical Systems

1.2 Input devicesInput devices can be described as:

a device that put electrical energy into a circuit

the environment can provide energy Input devices that we will look at are:

Electrochemical cell (battery) Generator Solar panel

Unit 1: Electrical Systems

1.2.1 Electrochemical cell (battery)

Unit 1: Electrical Systems

1.2.1 Electrochemical cell (battery)What is an electrochemical cell?

It is a device that uses a chemical reaction to create electrical energy

What is electrolyte? It is a liquid or gel that contains ions

What is an electrode? It is a solid electric conducting metal, it can be

positive or negative Negative electrode is called a cathode Positive electrode is called an anode

Unit 1: Electrical Systems

1.2.1 Electrochemical cell

What are the components of a electrochemical cell? Electrode of zinc (positive electrode - anode) Electrode of copper (negative electrode –

cathode) Two glass buckets filled with electrolyte

Unit 1: Electrical Systems

1.2.2 GeneratorWhat is a generator? Is a machine that converts mechanical

energy into electrical energy It is a machine that converts wind energy

into electrical energyDisadvantages of generators:

Wind generators need wind Birds can destroy the blades Diesel generators can be expensive Diesel generators are heavy

Unit 1: Electrical Systems

1.2.2 Generator

Unit 1: Electrical Systems

1.2.3 Solar panel (photovoltaic cell)What is a solar panel?

It converts light energy into direct current

Disadvantages of solar panels? They only operate in sunny climates Hail can damage it Panels can be vandalised They are expensive

Unit 1: Electrical Systems

1.2.3 Solar panel (photovoltaic cell)

Unit 1: Electrical Systems

Process DevicesWhat is a process device? it takes the electrical current and changes

it before it reaches the output devices

Process devices are: resistors

Unit 1: Electrical Systems

1.3.1 ResistorsAll materials can be grouped in three categories: Insulators Semi-conductors Conductors

Unit 1: Electrical Systems

1.3.1 ResistorsWhat is an insulator?

A material that cannot conduct electricity

What is a semi-conductor? A material that opposes the flow of electricity

What is a conductor? A material that allows the free flow of

electricity

Unit 1: Electrical Systems

1.3.1 ResistorsWhat are the uses of a resistor?

They limit the current They cause a drop in voltage They generate heat

Resistance is measured in ohms and is determined by four important factors:

The type of material How long the material is The area of the cross-section The temperature of the material

Unit 1: Electrical Systems

1.3.2 LampWhat is a lamp?

It is a device that converts electrical energy into light and heat

Disadvantages of a lamp: Some must not be touched when it is

burning Some lamps can heat up a room

Unit 1: Electrical Systems

1.3.3 HeaterWhat is a heater?

It is a devices that converts electrical energy into heat

Disadvantages of heaters: They can be dangerous They are expensive They use a lot of electricity Can cause fires They dry out the air

Unit 1: Electrical Systems

1.3.4 BuzzerWhat is a buzzer?

It is a devices that converts electrical energy into sound

Disadvantages of a buzzer: The sound can be irritating The sound will not carry far distances

Unit 1: Electrical Systems

1.3.5 MotorWhat is a motor?

It is a device that converts electrical energy into movement

Unit 1: Electrical Systems

1.4 Control Devices: SwitchesWhat is a switch?

It is a device that puts electrical energy into a circuit

There are different types of switches: Push switch SPST switch SPDT switch DPDT switch

Unit 1: Electrical Systems

2. Correct connections: Short circuitsWhat is a short circuit?

It is a low resistance in a circuit Or a weak point in the circuit

Short circuits prevent the follow of electricity

Unit 1: Electrical Systems

3. Electrical componentsSee the table on page 161

You must learn the whole table

Unit 3:Electrical systems and control

Batteries and bulbs in parallel

Advantages DisadvantagesHas the same current all around the circuit

If one bulb stops working the other will still work

Unit 3:Electrical systems and control

Batteries and bulbs in series

Advantages DisadvantagesCan add more power

Increase the resistance

  If one bulb stops working all will go out

Unit 3:Electrical systems and control

4. Photovoltaic cellsWhat is photovoltaic cell? It is a solar panel

UNIT 3: PHOTOVOLTAIC CELLS

Advantages of a photovoltaic cell: Produce pollution free energy Can be used

for years with little maintenance Useful for areas that don’t have electricity Sun shine is always available Save you a lot of money Disadvantages: It costs a lot to install Will not work well if weather is cloudy for

long period of time

Unit 4:Electrical systems and control

1.Thermal power stations

Unit 4:Electrical systems and control

2. Nuclear energy

Unit 4:Electrical systems and control

3. Solar energy

Unit 4:Electrical systems and control

4. Hydroelectric power stations

Unit 4:Electrical systems and control

5. Wind-driven turbines

Unit 4:Electrical systems and control

6. Alternating current 6.1 Step-up and step-down transformers 6.2 Distributing electric power across the

country 6.3 National grid

Unit 4:Electrical systems and control

Unit 4:Electrical systems and control