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dual FOCUS

Technology

2 SECONDARY EDUCATION www.anayaeducacion.es

SUMA

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Suma Piezas is an educational project by Anaya for Secondary Education.

The following people have worked on this book: Editorial team: Karen Piper, Ángela Vázquez and Caja Alta Edición & Comunicación (adaptation of the material from the book Tecnología 2º ESO). Design, technical drawings and maps: Patricia G. Serrano, Juan Carlos Quignon, Miguel Á. Castillejo, Miguel Á. Díaz-Rullo Illustrations: Celia López and Pablo Vázquez. Layout: Milagros Recio. Translation: Mariano Guirao. Photographs: Age Fotostock (Javier Larrea, Science Photo Library), Alamy/Cordon Press (Jose Lucas), Archivo Anaya (Canto, M.; Cosano, P.; Martín, J. A.; Martínez, C., Ortega, Á.; Osuna, J.; Peñuela Py, E.; Sánchez, J.; Steel, M.; Vázquez, A.), Dreamstime, iStock/Gettyimages, 123rf and collaborators.

Commitment to Sustainable Development Goals Our publications contain carefully selected content, illustrations and language to comply with nondiscrimination on the grounds of gender, culture or opinion. Grupo Anaya considers social and environmental responsibility to be one of its fundamental values. For this reason, we are committed to: · continually improving our contents and materials related to the environment. · reducing our carbon emissions. · using natural resources responsibly. · making sure that our activity has no negative consequences for endangered forests. These commitments, among others, mean that 100% of the paper used in our books has the PEFC label.

Important information: The activities proposed in this book should be completed in a separate notebook or on sheets of paper, not in the book itself. The links to webpages which appear in this book have been checked before printing. The publisher cannot be liable for any changes or modifications which occur after the date of publication.

© GRUPO ANAYA, S.A., 2021 - Juan Ignacio Luca de Tena, 15 - 28027 Madrid - Printed in Spain. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of the publishers.

Index 1. TECHNOLOGY MARKS THE PROGRESS OF SOCIETY.................................................................................. 7 Vocabulary • 1 Progress of humankind thanks to technical know-how • 2 Repercussions of technical activity • 3 Environmental impact of technological activity • 4 The process for solving technological problems • 5 Workshop and technology work • The final challenge: Prepare a budget

2. TECNOLOGICAL PRODUCT DESIGN.............................13

5. ELECTRICITY..............................................................................39 Vocabulary • 1 An electric circuit and its components • 2 Properties of the electric circuit • 3 Energy sources • 4 Generation and transport. energy efficiency • The final challenge: Electrical measurements

6. HARDWARE AND OPERATING SYSTEMS................47 Vocabulary • 1 Computer • 2 Central processing unit • 3 Peripherals • 4 Operating systems • The final challenge: Intelligent purchase of components and peripherals

Vocabulary • 1 Graphic communication: a universal language • 2 Tools and materials for drawing • 3 Freehand drawing • 4 Scales • 5 Projections and views of an object • 6 Perspective • 7 Digital graphics • The final challenge: Signage in public spaces

7. SOFTWARE AND APPLICATIONS..................................55

3. MATERIALS IN TECHNOLOGY: WOOD AND METALS...............................................................21

8. THE INTERNET..........................................................................63

Vocabulary • 1 Materials • 2 Properties of materials • 3 Wood • 4 Uses of wood • 5 Woodworking tools • 6 Metals • 7 Ferrous metals • 8 Non-ferrous metals • 9 Metalworking tools • 10 Metalwork • The final challenge: Make a sound box

4. STRUCTURES AND MECHANISMS...............................31 Vocabulary • 1 Structures • 2 Forces • 3 Structural components • 4 Types of structures • 5 Profiles and trusses • 6 Mechanisms • The final challenge: Lightweight structures

Vocabulary • 1 Software and licenses • 2 Word processors • 3 Electronic presentations • The final challenge: Install Ubuntu

Vocabulary • 1 Concept, advantages, disadvantages and risks • 2 Internet operation and protocols • 3 The Web, the HTTP protocol and browsers • 4 Email address • 5 The social web • 6 The Internet of Things • 7 Cloud Computing • 8 The internet and the law• The final challenge: Create your first website with BlueGriffon

9. INTRODUCTION TO PROGRAMMING........................ 69 Vocabulary • 1 Computer language • 2 Scratch • 3 Creating apps with App Inventor • The final challenge: Distributing an app

DUAL FOCUS

du al FOCUS

k oo b r u o y f o t In this par ind... you will f

TECHNOLOGY

Technology

SECONDARY EDUCATION

piezaS

cacion.es www.anayaedu

Focus on English

TECHNOLOGY MARKS THE PROGRESS OF SOCIETY

SUMA

This section contains activities for practising and applying the key vocabulary in the unit.

Scan this code to consult the glossary for this unit.

Progress of humankind thanks to technical know-how

Repercussions of technical activity

Atmospheric pollution Consequences of human activity on the environment

Water contamination Soil contamination

Environmental impact of technical activity

Climate change

The Final Challenge

Sustainability in industry

TECHNOLOGY MARKS THE PROGRESS OF SOCIETY

Definition of the problem Generation of ideas and search for solution

Each unit ends with a task or challenge to help you develop your skills by applying your knowledge in a different context.

Design Projects method

Process for solving technological problems

If it does not meet the conditions or does not work

Planning Construction

Teamwork

Evaluation Disclosure/Communication

Vocabulary The page that shows the key vocabulary you will encounter in the unit.

Technology workshop

Focus on English Risks in the workshop

1 Listening and Speaking. Listen and

Workshop and technology work

Reducing workshop risks Safety signs

BANK LANGUAGE LANGUAGE BANK BANK LANGUAGE LANGUAGE BANK LANGUAGE BANK BANK GE NK UA NK BA NG BA LA UAGE NGUAGE BANK BANK LAUAGE BANK LABANGNK LANGUAGE LANGUAGE LANG LANGUAGE

repeat the words to improve your pronunciation.

2 Reading and Writing. Use the branches of the outline to create three sentences about the environmental impact of technological activity.

The final challenge

MAKE A SOUND BOX Did you know that in a string instrument the string makes the sound, and the sound box amplifies the sound? In this project we will make a sound box.

STEP

Materials and tools

RESOURCE BANK

• Wood glue to join pieces (or hot-melt silicone). • Strip of soft wood with cross section 10 x 10 mm.

Go to anayaeducacion.es to find a wide range of resources to help you consolidate and expand your learning.

• Threads made of different materials (nylon, sewing thread, rubber bands, etc.) • Four 10 mm length screws. • Compass for marking. • Fretsaw to cut the wood, or a box cutter, depending on which material is used.

THE PROC ESS FOR SOLVI

NG TECH NOLO GICAL PROB

LEMS

The technology

s examples The textbook include object analysis with solutions of a project using and how to plan , which is a very a Gantt diagram purpose. useful tool for this

EX EC

Project management cycle

ON TI

DE S

P R O J E C T

S SI Y

tools. improper use of handle electrical these, do not origin. To avoid • Of electrical instructions. follow teachers’ hearing installations and or tripping, minor l damage, slipping ces. • Other risks. Postura or corrosive substan or contact with toxic loss due to noise

Reducing workshop

risks

measures: certain preventive know and apply dings and avoid It is important to with your surroun Become familiar • Organisation. ents. unless you are unnecessary movem Don’t use any tools tools. the with • Being familiar help prevent aware of their risks. riate clothing to calm and wear approp • Attitudes. Keep ing. accidents from happen e, if necessary purpos intended tools for their other appropriate or • Prevention. Use glasses and wearing gloves, under supervision ent. material. protective equipm with the working helps us to be familiar • Maintenance. It

take in of the actions to PAH is an acronym . case of accident

Protect to prevent another accident from happening

Alert

A L

gate... Understand, think, investi

workshop and is the technology of an is used often in reaching This type of work 4 Perform a full analysis and responsibility, day, shared leadership tasks to benefit object you use every characterised by and distributing bag. key to making decisions such as your book of conflicts. They agreements for ion resolut as a positive and their good the group, as well of its members tment commi the is r. a team’s success role of each membe regardless of the video communication, n.es and watch the Go to anayaeducacio problems’. solving technological ‘The process for

Find model examples and guided practices both in this book and in Tecnología 2º.

STEP

Assemble the box Put together all the pieces to make the box using glue. You can even reinforce the edges (the sides of the box) with more wood strips. Finally, lace and tighten four different threads between each pair of opposing screws and seal the edges.

Help

Go to anayaeducacion.es for information on the main targets of SGDs 15 and 16.

the victims, provided are you know what you doing

Safety signs

Warning

Prohibition

Commitment to SDGs

Mandatory

Fire safety g types Information can find the followin d terminology we According to standar am. These of signs: ound, black pictogr lar, yellow backgr DANGER • Warning. Triangu DANGER hazards. Danger inner circle. indicate potential Safety information ring and a white with a red outer DANGER • Prohibition. Round, performed. that must not be ion DANGER They show actions indicate an obligat pictogram. They DANGER white blue, DANGER • Mandatory. Round, action or rule. gate... certain a am. investi with to comply stand, think, Under black or white pictogr DANGER or rectangular, blue, Square tion. • Informa tion. of safety the location Simply provide informa 5 How many types am. They indicate What do , red, white pictogr signs do you know? • Fire safety. Square What colour ishers, etc. ound, they represent? of hoses, extingu ular, green backgr each one? tion. Square or rectang is associated with • Emergency informa ncy exits, etc. one in emerge seen ever indicate These Have you am and the white pictogram. right, black pictogr school? outer red your a hazard lar, with • Danger. Triangu for writing the specific hazard and a space word danger or it. in

The resource bank contains audiovisual material that focuses on Sustainable Development Goals.

Model example

Make the cover Cut two blocks from the strip of wood that are a bit shorter than the width of the cover. Place four screws in each one with equal spaces between them. Then join the two blocks to the cover at the opposite ends of the circle that you cut out, making sure that they are parallel to each other and to the edges of the box.

the person in charge or the emergency services

Safety signs N

Teamwork

Model example

Project memory design, planning s related to the technical aspect Describes all the of the object. and manufacturing the project, sheet (name of ts, at least a cover table of conten y), It must include deliver of group, and date , possible information on the tasks in the group) d ution of times and n selected (forme organisation (distrib r) and the solutio membe each assembly for solutions (one g of the parts, the ed, the the object, the drawin of subject views be the will by the object tests to which used, a page with tools instructions, the of table a of materials and raphy and budget, a table member, and bibliog s of each group the personal opinion ces). websites referen

shop

g tools the the risks of handlin s being aware of Prevention require g the rules of use. wrong way and applyin the workshop are: The main risks in injury due to the cause may s origin. Some activitie • Of mechanical

s Analysis of object can be used to of analysis that different types of the object), There are four (structure or shape : morphological properties) propose a solution al (materials and ion and use), technic one that meets all functional (operat object will be the ideal The . (costs) and economic e cost. with the lowest possibl ments require the

The PAH approach

workshop

Risks in the work

ST E

ng a series of s are solved followi by which problem This is a process steps or stages: analysing, ing for information: a problem; 2) Search ; 3) Designing 1) Defining of the solution a g ideas, and choosin and selecting coming up with ed-view drawings, and general and explod ing of the work sketch, drafting g: budgeting, organis Plannin testing: 4) and ls; tion the materia cturing; 6) Evalua ons and tasks; 5) Manufa the conditi ting the distribu ance with checking compli completing the operational tests, prototype and Presenting the memory. the process; 7) 8 Completing the project documentation. obtained step, if the result evaluating and testing d conditions or does Upon reaching the meet the require not does and go over the shows that the object back to step three ly, you must go not work correct again.. remaining steps s there are two logical problem of solving techno specification. In this process and the technical analysis of objects essential tools: the

Unit 1

GY WORK

it to prevent while working in must be observed The workshop rules accidents.

Project method

Mark and cut six square or rectangular pieces on the board, with the dimensions that allow making a cube or a prism with them. Then saw a circle in the part that will be the cover by drilling a hole and inserting the fretsaw in the hole to cut out the circle.

• Glue gun.

STEP

WORKSHOP AND TECH NOLO

Mark and cut

• A board (5 to 8 mm thick plywood, or cardboard).

Basic exercises The activities on these pages work on the basic unit content, as well as the different language skills.

DUAL FOCUS

du al FOCUS

…

ON SECONDARY EDUCATI

t r a p is h t in d An

Technology TECHNOLOGY

CE BANK RESOURpanie s this book.

Go to the

that accom Available

ducacion.es

at www.anayae

UNIT

788469

887226

In this section of the book, the key information is presented in graphic form, using diagrams and illustrations to help you learn each concept.

SUMA

piezaS

8430981

DUAL FOCUS

98-8722I S B N 978-84-6

Key concepts

SECONDARY EDUCATION

SOF TWA RE AND APP LICA

TION S

Word processor

t written documents

Create, save, edit and forma

Software

Application software

User interface

rams. executable prog Software: set of hine to ns given to the mac Program: instructio e a task. complet

allows

Word processor

Office tools Application software

Operating system

raph and • Editing character, parag document attributes s and other • Including tables, image graphic elements

work Automating office adsheets, (writing texts, spre , etc.) making presentations

User Interface Application software

cessor Working with a pro

Operating system Hardware Hardware

Maintenance programmes web services T access + use of Internet UNI

re Communication softwa

Typing area

Right margin

Left margin

Office tools

Licenses

Proprietary software

1. Select text 2. Insert 8 Section 3. Set number

Insert columns

1. Select text 2. Page layout 8 column configuration

Word Writer

Footer area Bottom margin

Presentation Assistants

Word

Table 8 Insert 8 Table Insert 8 Table Insert menu

cs Insert images or graphi

LibreOffice Impress environment

Computer applications to develop slides, which together form a presentation. Free software

WordArt

Word Writer

Insert tables

Games and entertainme applications

Fontwork

Writer Insert artistic text

licenses Application software and

Utilities software

Format menu

Modify Font, Paragraph or Page

Top margin Page header area

Application software

COMMAND OR MENU

TASK

Computer layers

Toolbars

nance and improvemen

Collaboration in mainte

No changes allowedOffice

tools

user 8 to limit between author and Legal agreements use of the software the

Presentation assistants

Microsoft PowerPoint LibreOffice Impress

Create slides

Slide pane Microsoft PowerPoint Work area

Presentation

Task Pane

Visual and attractive method to present ideas 8 and convey concepts.

Creation and dynamisation of slides

LibreOffice Impress TASK

Tips for presentations • Adapt the contents to the receiver. • Choose an appropriate font and size to maintain formatting. • Avoid slides with too much detail or too complex. • Use 6-8 lines per slide. • Avoid vertical text. • Use high contrast colours. • Don’t abuse transitions and animations. • Use good quality images.

Activities The resource bank contains activities for you to practise what you have learnt.

• Be creative, but prioritise understanding. • Check that the presentation is compatible with the media used (files, audio...). • Do not read aloud the text on the slides. 28

Create slide

COMMAND OR MENU IN IMPRESS Insert 8 New Slide Duplicate slide

Distributing content on a slide

Task Panel

Slide style

Master slides 8 Apply to selected slides

Insert text boxes, images, etc.

Drawing

TASK

Text boxes Images, video and sound Other visual elements

Transition Animation

anayaeducacion.es You can use the activities in the resource bank to review the content of these fact files.

COMMAND OR MENU Add objects Impress

Drawing 8 Text 8 Selection

Insert 8 Text box Insert 8 Image (Video or Sound) Impress SmART PowerPoint WordArt Animate presentations PowerPoint

Transition tab Animations tab

The

Resource bank www.anayaeducacion.es

This is where you will find resources, techniques and activities to help you consolidate your knowledge. Go to www.anayaeducacion.es, and follow the steps at the beginning of your Spanish book.

STRUC TURES

Structures are complex objects meant to support certain loads (such as a house).

Loads and balance of

A structure’s design A structure is made up of a series of solid elements, joined and attached together to support all kinds of loads.

A termite mound built

by termites. 28°C

Copying nature

24°C

Copying natural const

ructions

Your book contains references to the online resources you can use to learn more about each topic and to develop your English language skills.

Air flow inside the building

in Harare based on a termite mound.

Understand, think, investigate... 1 What is the function of a table top? And of its legs?

FORCE S

What are forces?

Forces are pushes or pulls characterised by their value or intensity or by their orientation. , Forces make changes to bodies: they can change their shape (deforming them) or their movement (changin speed or direction). g

How are they measu

red?

There are several instrume nts for measuring forces, such as scales or the dynamometer, which is based on the ability of a spring to extend proportionally to the force applied.. Units of measurement Mass is measured in kilogrammes (kg) in the International System (SI). Forces are derived from mass, so the International System uses the newton (N), defined accordin g to the expression: 1 N = 1 kg · m/s2. 32

Centre of gravity

Cube

Circle

Dynamometer Mobile

20 kg

band for marking the weight Hook

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 kg

Ring Spring Extendable graduated ruler with the spring

Understand, think, investigate... 2 A block of stone has a

mass of 100 kg. What would its weight be (the force with which the Earth attracts it) if the accelera tion due to gravity is g = 9,8 m/s2 ?

An object or structur e is stable when its mass distribution is balance when the forces of gravity d act on it. The centre of gravity is defined as a geometrical point representative in the body of an object in which we imagine all its mass is concentrated. For example, the centre of gravity of a symmet rical body is the geometrical point at which all the diagona l lines that join the opposin vertices cross. In figures g lacking symmetry, this point can be located out of the body, which indicates a lack of stability.

Types of forces and

Loads created by forces

When a set of forces acts on an object, the object is deformed internal forces known by as stresses. There are five types of stresses : • Tension: two forces stretch the body and therefore increase its length. • Compression: forces act on the body and shorten it and make wider. it • Bending: forces bend

or curve a body.

• Torsion: we twist and object by applying to it two rotational forces in opposite direction s. • Shearing: an object is cut when two forces that act on it in different directions.

In anayaeducacion.es you can find a simulatio n that will help you understand forces.

Asymmetrical

Deformation Sand mound Representation of the weight of the sand as it accumulat es.

Reaction of the structure to support the weight of the sand.

loads

There are two criteria for classifying forces and loads. Accordin their duration and magnitu g to de, they can be fixed (constant magnitude and direction) or variable (changing magnitude and direction). And, depending on how they are applied, they can be concentrated (located at one point of a surface) or distribu ted (distributed over surface). a In the example of deforma tion shown, you can see that with more sand in the mound, the load at the centre increases, which is where the deformation will be greater if the structur e is not very resistant .

Triangle

shape

The centre of gravit y: a key concept for stability

Natural structures (such as the walls of a cave, or the weight distribution in a tree), can be used to create improved structures. The animal kingdom also provides example s of structures. Beavers for example, build dams , to protect their homes.

Nature has inspired the design of many structures. This explains development of biomimi the cry, a field of science that studies biologic structures to solve al human problems by looking at nature. example, in Harare (Zimbab For we), an air conditioning system has been created based on how termites cool their mounds using air currents.

Unit 4

an object

A balanced structure is affected by multiple forces. All forces acting on it need to add up to zero (otherwise, the body will be subjecte acceleration). The forces d to that appear due to the weight the structure supports are called loads. Loads can be classified into static do not change over (that time), dynamic (that can change over time) accidental (such as those and due to meteorological phenomena).

Distribution and effect

of a sand mound on a platform.

Types of stress Tension Compression

Bending

Shearing Torsion

Understand, think, investigate... 3 Indicate at least one example of concentrated forces and one of distributed forces in daily life.

Resources organised

by unit

Interactive activities

All the resources are clearly organised so you can find the ones related to your unit.

l Audiovoisuuarces

res

Glossary

Scan this code to consult the glossary for this unit.

ELECTRICITY Concept and components

Generators

Cells and batteries, alternators, power supplies

Conductors

Electric current

Loads

Light and heat emitters, motion generators, other

Control and protection elements Electric current

Symbols Resistance Properties

Power

Ohm’s law In series

Connections In parallel

Electricity

Renewable

Solar, wind, geothermal, biomass, hydraulic

Non-renewable

Coal, petroleum, natural gas, nuclear energy

Sources

Energy Production Generation and transport. Energy efficiency

Transport Transformation Energy efficiency

Focus on English 1 Listening and Speaking. Listen and repeat the words to improve your pronunciation.

2 Reading and Writing. Use the branEnergy labels

NK A B E G A NK U A G B N E A L G A U G LAN NK NK A B E G K A N U A G B E BA AN G L E A G U A G U N G A K N L N A L BA LANGUAGE ANGUAGE BANK NGUAGE BANK BANK

ches of the outline to create three sentences about the elements of an electric circuit, non-renewable energy sources and energy efficiency.

AN ELECTRIC CIRCUIT AND ITS COMPONENTS

An electric circuit is a closed path made of materials that conduct electricity, in which some components are connected by wires through which electric charges can flow. These components are generators, conductors, loads, control elements and protection elements.

Focus on English Direct current: provided by batteries. Its value is constant. Alternating current: flows through the power grid and reaches homes. Obtained from alternators. Its value is variable.

Generator Provides the energy for the electric charges which move around the circuit. It is an essential element and can be classified as: • Batteries: contain chemical substances that generate electricity when they react. When these substances allow the reaction to be reversed, they are called rechargeable batteries. • Alternators: alternating current machines that generate electrical energy in the form of waves. • Power supplies: electronic devices that transform alternating current into another form of electrical energy, such as direct current. The energy measurement (charge difference) is known as voltage or electric potential. This magnitude indicates the amount of energy supplied to each electric charge. It is measured in volts (V).

Conductors

Voltage =

Energy E ;V= Electric charge Q

E is the energy expressed in joules (J), Q is the electric charge in coulombs (C) and V is the voltage in volts (V). Electric = Charge ; I = Q current Time t

Model examples

Conductors allow electricity to flow from the generator to the loads. In contrast, insulators do not allow electricity to pass, and are therefore used in circuits to prevent it from going where it should not go. Electric current is the movement of electric charge along a conductor when it is connected in a closed circuit with a generator. The charges move, creating a flow of electric current through the conductors. It is a continuous and ordered movement of electrons through the different circuit elements. To find out if the flow is low or high, we use the electric current, which is the measure of the number of charges that pass through a particular point of the circuit in a unit of time. It is measured in amperes (A).

Loads These are the elements that receive and transform electrical energy. They all have a common property called electrical resistance, which is the opposition of the materials to the flow of current. The most common ones are light emitters, heat emitters and movement generators. • Light emitters. They transform electrical energy into light, like lamps. Nowadays, light-emitting diodes (LEDs) are commonly used to provide lighting. LEDs are made from semiconducting materials and use very little electricity.

Calculating voltage and current

In your textbook there is a table listing the types of materials according to their resistance. You can also find guided practice related to the voltage.

Types of light bulbs Your textbook shows the most common types of light bulbs.

Understand, think, investigate... 1 Air is an insulator (electricity does not flow from one terminal to the other in a plug). However, the electricity of a lightning bolt flows from the clouds to the ground. How can you explain this phenomenon?

At anayaeducacion.es there is an introductory video on what you will learn in this unit.

Unit 5 • Heat emitting elements. They transform electric current into heat in three different ways:

Open circuit, closed circuit

–B y conduction, when two bodies at different temperatures come into contact. For example, a clothes iron. –B y convection, through a fluid (liquid or gas) that conducts heat to places with a different temperature, like a hair dryer. –B y radiation, due to the internal temperature of a body. The higher the temperature, the greater the radiation. This is the case with infrared, halogen, or quartz heaters, etc. • Motors and elements that move. These are rotary machines that can generate electrical energy from mechanical energy. This is the case for electric motors, where the energy is obtained from the forces generated by the copper conductors of the motor as they move inside the magnetic field generated by the magnets of the motor. The most commonly used ones in the technology workshop are direct current motors.

Closed circuit: lightbulb on.

Electric motor

Electromagnetic relay Speaker

There are also motors in the pumps of washing machines and dishwashers, in blenders, juicers, and in DVD readers, some of which use direct current and some alternating current. • Other loads. There are other types of loads that transform electrical energy into other forms of energy. For example, speakers, buzzers and bells, electromagnetic relays, etc.

Control and protection elements These components allow or stop current from flowing through all or part of a circuit. There are three types:

Open circuit: lightbulb off. A circuit will be closed if all of its elements are connected and electric current flows through them. Instead, if it is open, current will not flow through it.

Remember In your textbook there is a table with the symbols used in electric circuits.

• Switches: they open or close the circuit. For example, light switches. • Push buttons: they open or close a circuit when pushed, as in a doorbell. There are two types: normally open (N.O.) and normally closed (N.C.). • Multiway switches: they open one circuit and close another. When they change position, they close the open circuit and open the closed circuit.

Symbols As in most technical activities, making a drawing or diagram is important to define electric circuits. To interpret them correctly, it is necessary to know the symbols used for the components of the circuit. Each component of an electric circuit has a symbol associated with + – it in the diagram. For example, the symbol of a battery is and the symbol of an alternator is .

Understand, think, investigate... 2 Make a table in your notebook with a classification of the different types of loads you have studied. Indicate the energy transformations that take place in each one.

3 What is the difference between a push button, a switch, and a multiway switch? Draw their symbols.

PROPERTIES OF THE ELECTRIC CIRCUIT

Resistance This is the difficulty that electric current encounters to flow through an object, and depends on its composition and dimensions. It is expressed in ohms (Ω). According to this opposition materials are classified into conductors, insulators, semiconductors and superconductors. In 1822, the German scientist George Simon Ohm stated Ohm’s law: the current in a circuit is directly proportional to the voltage across its ends and inversely proportional to the resistance of the circuit. The value of the voltage will depend on the battery or power supply; given this value, the current will be low if the resistance of the circuit is high, and high if the resistance is low.

Vocabulary Resistivity: a physical property that allows knowing if a material is a good or bad conductor. Equivalent resistance: replaces another resistance with the same effect as the replaced one. Watts: Joules per second. Its symbol is W.

Ohm’s law triangle

Power V

This is the amount of energy used in a period of time. It is measured in watts (W), defined as joules used per second (1 W = 1 J/s). The unit used for electrical energy is the kilowatt-hour (kWh).

I =

Connections

R =

Electric circuits are made up of more than one load, connected in different ways to form different types of circuits:

=I·R V R V I

• Series circuits. The loads are connected together one after another. If one stops working the rest will stop working too, as the current will not be able to flow. Magnitude

Explanation

Formula

Equivalent resistance

Sum of the resistances in the circuit.

Voltage

It is distributed among the different resistances. The sum of their voltages is the same as the voltage of the generator.

Current

It is the same for all the elements of the circuit.

Rt = R1 + R2 + ... + Rn Vgen = V1 + V2 + ... + Vn

Explanation

Equivalent resistance

Its value is the inverse of the sum of the inverse values of each of the resistances of the circuit. If there are two resistances, it is calculated as the product of the two resistances divided by the sum.

Voltage

The voltage is the same for all the elements connected in parallel.

Current

The current flowing through each branch of the circuit will depend on the resistance value for each branch. The total current provided by the battery will be the sum of all the currents flowing through the branches.

You will find model examples in your textbook for solving circuits with the nomenclature used.

I = I1 = I2 = ... = In

• Parallel circuits. The loads are connected to each other and to the voltage of the generator. The current can flow through more than one path. Magnitude

Model examples

Formula 1 1 1 1 = + + ... + Rt R1 R2 Rn

Understand, think, investigate... 4 What current will flow through a 90 Ω bulb when connected to a 4.5 V battery?

5 Show the steps needed to V = V1 = V2 = ... = Vn

I = I1 + I2 + ... + In

solve a parallel circuit and a series circuit. In both circuits, use two 15 kΩ and 5 kΩ resistances and a 5 V battery.

Practice making circuits with the virtual kit provided in anayaeducacion.es. You can also work with the virtual laboratory for Ohm’s law.

ENERGY SOURCES

Unit 5

There are two types of energy sources: primary sources, which include sources available in nature before transformation, and secondary sources, obtained from transforming a primary source, which can be stored, transported and used.

Renewable energies These are energy sources that do not run out when we use them. • Solar energy. Generated in the Sun from the nuclear fusion reactions that take place in its core. It reaches us in the form of electromagnetic radiation as visible light, infrared radiation and ultraviolet radiation. It is used for lighting, climate control, and other everyday tasks. • Wind energy. It is obtained from the wind; in reality it comes from the Sun heating the air. It is obtained using windmills which are installed in wind farms and generate electric energy. • Geothermal energy. It comes from the internal heat of the Earth. It is used for heating systems and to generate electricity.

Remember As well as coming from primary or secondary sources, energy can be classified as renewable or non-renewable. Both types are used to generate electricity.

Did you know? Petroleum and natural gas come from a heterogeneous mixture of hydrocarbons. They are different only in that natural gas is in gaseous state.

• Energy from biomass. It is obtained from organic material (plants or animals) and from transformed products. It is burned (to obtain electric energy and heat) or transformed (to obtain biodiesel).

Wave power

• Hydraulic energy. This is the energy contained in water, manifested in different ways, especially as kinetic energy. It is used in hydroelectric power stations, tidal power stations (using energy from tides) and wave power stations (movement of waves). Hydroelectric Intake channel Transformer

Tidal Power grid

Low tide

Generator

Nuclear fission Neutron

Water stored during high tide Transformer Turbine Generator

Turbine

Non-renewable energies They run out as they are used: they do not regenerate, or do so at a slow rate. • Coal. It is a fossil fuel of plant origin used in industry. • Petroleum. Of marine origin, it is used to obtain fuels, and to produce and transport electrical energy. • Natural gas. A mixture of hydrocarbons of fossil origin. It is the least pollutant one. Used for heating or cooking. • Nuclear energy. Obtained from the fission, or breakdown, of uranium-235 atoms, which release energy when broken. It is used to produce electrical energy.

Heavy nucleus The nucleus decomposes into smaller nuclei

Energy is released, as well as neutrons that hit other heavy nuclei

Understand, think, investigate... 6 What are the differences between renewable and non-renewable energies? List the existing types of energy.

GENERATION AND TRANSPORT. ENERGY EFFICIENCY

Production

Alternator

The electric current we use is generated in power stations provided with turbines and alternators. Each station uses a different energy source to move the turbine.

Rotor magnets

S N

N S

• Thermal power stations use the heat generated when burning coal, natural gas, wood or any other fuel.

Stator coils

• Nuclear power stations use the energy from nuclear fission.

Alternating current

• Solar power stations use the heat from the Sun.

Transport After electricity is generated, it must be transported to where it is used (industrial plants, homes, street lighting, etc.). Transmission and distribution lines are classified into low, medium, and high tension depending on their voltage. As it cannot be stored in large amounts, the electricity generated must be the same as the electricity used.

Drive shaft

Machine that transforms mechanical energy into electrical energy. It has a fixed part, the stator, and a mobile part, the rotor. It is made with conducting wire in which an electric current is induced by the magnetic fields generated by the magnets when they move.

Understand, think, investigate... 7 Look up the Joule effect and

Transformation Electrical energy is generated at a voltage between 5 and 25 kV (medium voltage). To reduce loss in transport, the voltage must be increased to between 222 kV and 400 kV (high voltage). At the time of consumption, in industrial plants and homes, it is reduced to 690 V and 230 V respectively. To change the voltage, substations use transformers.

the problems that it causes when transporting electricity across long distances. Why is it important to transport electrical energy at high voltages?

Transformation and transport of electric current TRANSPORT (High voltage: 220-400 kV)

SUBSTATION Transmission lines (69 kV)

GENERATION (Medium voltage: 5-25 kV) Distribution lines (12 kV) Industry

Consumption (Low voltage) 690 V Homes 220-230 V

DISTRIBUTION CENTRE

Unit 5

Energy efficiency Energy efficiency is the relationship between useful energy (Eu ) that we get from a system and the energy supplied to it (Es ).

Calculating efficiency

h =

Eu Es

A device is energy efficient it if has high energy efficiency; that is, if the device uses most of the energy supplied, while minimising energy losses. Because saving energy and reducing carbon dioxide emissions is very important, the European Parliament requires all electrical appliances to have an energy label showing their level of energy efficiency. Therefore, it is mandatory. Using energy-efficient electrical appliances allows saving energy and water, which contributes to a more efficient use of energy and natural resources.

Energy labels The following aspects stand out: • Brand and model. The name of the manufacturer and the model of the appliance. • Energy efficiency of the product. It shows the energy consumption category of the appliance, compared to the average consumption of electrical appliances of the same type. The highest category is the lowest energy consumption, and vice versa. • Annual electricity consumption (in kWh). Calculated based on standard conditions of use.

Remember Energy efficiency can apply to buildings, not only to devices. If energy efficiency is taken into account when building a house, it is possible to considerably reduce energy consumption (for example, by placing the windows so that they maximise the amount of natural light or using insulating materials that reduce heating consumption). It is also possible to install solar panels, water purifiers and other means that make use of natural resources.

• Other characteristics. According to the type of appliance. For example, in a washing machine, litres of water used per wash, amount of clothes it can wash, and noise. • QR Code. Included in devices with modern labels, it provides access to a description of the model in the European Union registry database. UNDERSTANDING THE LABELS Using an average class G refrigerator as a reference

Most efficient

Medium consumption

High energy consumption

Less than 20 %

Between 20 % and 30 %

Between 30 % and 40 %

Between 40 % and 50 %

Between 50 % and 70 %

Between 70 % and 85 %

Between 85 % and 100 %

Brand and model Energy efficiency of the product Annual electrical consumption (in 100 cycles)

Understand, think, investigate... 8 Find out the meaning of the following pictograms and say which type of electrical household appliances you could find them on:

Other characteristics of this type of appliance

ELECTRICAL MEASUREMENTS

The final challenge

STEP

In this project, you will assemble a circuit and check your calculations using a multimeter.

STEP

Study the circuit

Elements and measurements

In a parallel circuit there is a 3 V battery connected to two 220 Ω and 1000 Ω resistors (the diagram is shown in the figure). We will calculate the current and voltage in all the circuit elements.

+ 3V + 3V + 3V

It It It

I1 I1 I1

I2 I2 I2 0,22 kX 0,22 kX 0,22 kX

1 kX 1 kX 1 kX

Req Req Req

To assemble the circuit, you will need: • A breadboard • A 1 kΩ resistor and a 220 Ω resistor. • A 3 V battery mounted using two AA 1.5 V batteries. • A digital multimeter. First measurement: Equivalent resistance It is important NOT to connect the batteries to the circuit. Copy the circuit shown in the image. Note that the multimeter is used to connect the parallel assembly of the two resistors. Change the selector to the correct scale in the sector with the Ω symbol and record the value. Second measurement: Total current in the circuit Connect the battery to the same points where you connected the multimeter previously. To measure the electrical current, connect the multimeter in series. Prepare the assembly and note how the red wires are connected to the points of the circuit with the highest voltage. Change the selector to the correct scale in the sector with the A symbol and record the value.

STEP Check results and analyse errors

• To analyse the errors, we will use the absolute error (the difference between the value we calculated and the value we measured) and the relative error (the absolute error divided by the calculated value, multiplied times 100 to obtain a percentage). • Copy this table entering the values you have measured and calculate the errors. Do you think the relative error percentages are low? Can the measurements be considered correct? Explain your answers.

Magnitude

Calculated Measured Absolute Relative value value error error

Equivalent resistance

180 Ω

Current in the circuit

16,63 mA

Look up targets 7.3, 11.6, 12.8 and 13.3 in

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UNIT

ELECTRICITY

An electric circuit and its components

The symbols allow understanding a circuit. Alternator:

Closed path made of a material that conducts electricity, in which some components are connected by wires through which electric charges can flow. Generators (voltage)

Cells and batteries, alternators, and power supplies

Conductors (electric current)

Allow electricity to flow. This flow is prevented by using insulators

Components Light and heat emitters (conduction, convection and radiation), motion generators and others

Loads (electrical resistors)

Switches, push buttons (NO and NC) and multi-way switches

Control and protection elements

Electric magnitudes, units of measurement ad formulas Electric magnitudes are calculated with formulas and have their own units of measurement. Magnitude

Unit of measurement

Voltage (V): amount of energy (E) supplied.

Volt (V)

Current (I): number of charges that pass a point of the circuit in a unit of time.

Amperes (A)

Resistance (R): difficulty presented to flow of current. Power: the amount of energy used in a period of time.

Formula Energy Charge

Voltage =

; V=

Charge Q ; I= Time t

Ohms (Ω)

Resistance =

Volts ; R = V/I Current

Watts (W)

Watts =

Current

Joules ; 1W=1J/1s Second

tor, semiconductor Types of materials according to their R: conductor, insula and superconductor. 18

E Q

Ohm’s law

The I that flows in an electric circuit is directly proportional to the V applied and inversely proportional to the R of the circuit. V =I•R V I = R V R = I

Arrangement of the circuit

An unlimited number of loads can be connected. Loads connected one after each other.

In series

Set of loads

Circuits Loads connected to each other and to the voltage source.

In parallel

In series

In parallel R1

Three resistors connected in parallel.

Three resistors connected in series.

R2 R3

Two resistors connected in parallel.

Two resistors connected in series.

R2 Rn

n resistors connected in series. n resistors connected in parallel.

Formulas for circuits Magnitude

Series circuit

Parallel circuit

Equivalent resistance

R t = R 1 + R 2 + ... + R n

1 1 1 1 = + + ... + Rt R1 R2 Rn

Voltage

Vgen = V1 + V2 + ... + Vn

V = V1 = V2 = ... = Vn

Current

I = I 1 = I 2 = ... = I n

I = I 1 + I 2 + ... + I n

uni

D DA

Energy sources

Sources that do not run out when we use them.

Nuclear fusion (Sun)

Solar

Wind + turbines

Wind

Heat (Earth)

Geothermal

Biomass

Renewable

Organic matter and transformed products

Hydraulic

Water (kinetic energy)

Sources that run out when we use them.

Electromagnetic radiation.

Visible light. Infra-red radiation. Ultraviolet radiation.

Electric energy. Sail boats, windmills, etc.

Electric energy. Heating systems.

Combustion = electricity and heat. Transformation = biodiesel. Transformation in hydroelectric plants, tidal energy plants and wave energy plants. In addition to generating electric energy, they are used for:

Non-renewable

Coal

Fossil fuel (plant matter)

Petroleum

Marine origin

Transportation (fuels), plastic, asphalt.

Natural gas

Fossil origin Not very polluting

Heating and cooking.

Nuclear energy

Fission of uranium-235 atoms

Nuclear weapons (destructive purpose).

Industrial use. Manufacture of steel.

Generation and transport of energy Production Generating electricity in an electric plant (turbines + alternators). Use of different sources (heat, uranium, Sun).

Transformer 8 Changes the voltage

Transport

Transformation

Consumption

Transport to consumption points 8 low, medium and high tension lines.

Increase voltage to prevent losses in transport. Lower voltage 8 for consumption.

Homes Buildings Urban facilities, etc.

Energy efficiency Energy performance 8 Energy efficiency Maximum use + minimal losses

Energy labelling Brand and model

• Required by European Parliament (home appliances) 8 energy savings + lower CO2 emissions. • Identifies the energy efficiency level. Energy label fields Brand and model Consumption compared to the Energy efficiency class average of the same type of device. (A – G) (+ category, - consumption) Annual electricity consumption Calculated in standard conditions. (kWh) Other characteristics QR Code

Energy efficiency of the product

Electrical consumption (annual or in 100 cycles) Other characteristics of this type of appliance

Description of the model (European Union database)

anayaeducacion.es You can use the activities in the resource bank to review the content of these fact files.