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 devices Input 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 Generator What is a generator? Is a machine that converts mechanical energy into electrical energy It is a machine that converts wind energy into electrical energy Disadvantages 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 Devices What 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 Resistors All materials can be grouped in three categories: Insulators Semi-conductors Conductors

Unit 1: Electrical Systems 1.3.1 Resistors What 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 Resistors What 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 Lamp What 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 Heater What 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 Buzzer What 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 Motor What is a motor? It is a device that converts electrical energy into movement

Unit 1: Electrical Systems 1.4 Control Devices: Switches What 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 circuits What 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 components See the table on page 161 You must learn the whole table

Unit 3:Electrical systems and control Batteries and bulbs in parallel Advantages Disadvantages Has 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 Disadvantages Can add more power Increase the resistance   If one bulb stops working all will go out

Unit 3:Electrical systems and control 4. Photovoltaic cells What 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