Download SUBJECT NATURAL SCIENCES Grade SCIENCE 11th

 SUBJECT NATURAL SCIENCES Grade Learning unit SCIENCE 11th How do we transform the planet? GRADE What is the origin of the electric power we use at home? title of Learning object Curricular axis Physical environment Standard competencies Relate voltage and current with the different elements of a complex electric circuit and the entire system. Learning objectives 1. To know the basic principles for transport and use of electric energy. 2. To compare the environmental impact and benefits of power plants objectively. 3. To take advantage of electric energy at school and at home. 4. To exchange information about concepts related to electricity. skills/ knowledge SKILL 1: Explain the relation between electric current and the flow of charges. SKILL 2: Explain similarities and differences between alternating current (AC) and direct current (DC). SKILL 3: Prove Ohm's law. LEARNING FLOW SKILL 4: Interpret diagrams of series and parallel electric circuits, and make an electrical drawing of their home or classroom. SKILL 5: Analyze the environmental impact of thermopower and hydropower plants in Colombia. SKILL 6: Carry out research on the losses of energy caused by transport through high voltage lines. SKILL 7: Review studied concepts by practicing with passive voice sentences. Introduction Activity 1: Electric charge Current direction Direct Current (DC) Alternating Current (AC) Direct current vs alternating current Activity 2: Voltage Resistance Ohm's Law Electric circuits Series circuit Parallel circuit Activity 3: Hydropower plant Thermopower plant Environmental impact ASSESSMENT GUIDELINE Distribution Networks Abstract Homework Evaluation Bibliography Glossary Vocabulary box English Review Topic In this learning object the student is expected to understand how electricity works from the flow of charge determining current, voltage and resistance to the diagrams of electric circuits in series and in parallel. Additionally, the student will be able to transfer this knowledge to a social scope, and critically think about the environmental impact caused by hydroelectric and thermoelectric plants in Colombia. Stage Introduction Learning flow Introduction Teaching/Learning Activities Show the introduction. It presents the topic in general by means of a question useful to know how much students know about it. You can present the contents of this learning object. We use electric devices everyday such as cell phones, computers, appliances, bulbs, lanterns, and TV remote controls, among others. Electricity is part of our everyday life; something essential for everything we do. However, we may not know the difference Recommended Resources Animation Content Activity 1 between the electric circuit of a lantern and the electric circuit of a bulb at home. Do you know why you have to use an adapter to connect your cell phone, but you can connect the TV directly to the wall at home? You will be able to answer this and other questions through this learning unit. Additionally, you will find interesting information about electrical networks in our country. The following skills are developed in this activity: Skill 1. SKILL 1: Explain the relation between electric current and the flow of charges. Skill 2. SKILL 2: Explain similarities and differences between alternating current (AC) and direct current (DC). In this first section, present the concepts of electric charge and electric current Electric charge All matter is formed by atoms, which are made of protons of positive charge, electrons of negative charge and neutrons without electric charge. Protons and neutrons are in the nucleus, while electrons are outside the nucleus. Protons have the same amount of charge as electrons, but with a different sign. Atoms have the same number of protons and electrons. Consequently, atoms are electrically neutral. Electric charges may interact by means of attraction or repulsion depending on their signs. Movement of electric charges. Animation, Infographics, Multimedia Electric current is the continuous and ordered movement of electrons through conductive material. They always move from the (­) pole to the (+) pole of the power supply. Current intensity (I) is the amount of net charge (Q) passing through a conductive element in the time unit (t), and it is measured in amperes. I=Qt Use the following information as fun fact. Elicit whether students know more interesting information they can share. Did you know?​
When they were trying to explain how electric current flows through materials, the scientific community did not know about electrons. Explain here how a direction has been given to current conventionally. It is important to explain the examples about the effects of current. Current direction Charged particles passing through a surface can be positive, negative or both (positive and negative). As a rule of thumb, current is given the same direction of the flow of positive charge. In electric wires made of materials such as copper or aluminum, current is created by the movement of electrons of negative charge. As a result, the direction of current is opposite to the direction of the flow of electrons: Effects of electric current Current can cause some effects on the materials it crosses, including: • Emission of heat, for example, an iron. • Chemical effects, for example, electrolysis. • Magnetism, for example, electromagnets. Reminds students about the concept of electrolysis. Remember that electrolysis is a chemical process where the elements of a compound are separated by means of direct current. This part works on the concepts of direct and alternating current. Use images as support to clarify the concept. Direct Current (DC) It is the continuous flow of electrons through a wire, as a result of potential difference. If two plates charged with different signs are connected through a conductive wire, the free electrons of metal will be repelled by the negative plate, and they will move to the positive plate, creating a flow of electrons from the negative to the positive plate by means of the conductive wire. Atoms forming the metal wire do not move, only some of their electrons move. Electric charges always circulate from the highest voltage terminals to the lowest voltage terminals, that is, always in the same direction. The current that always keeps the same polarity is direct current. Alternating Current (AC) It is the vibration of electrons inside a conductive wire. Electrons vibrate at a specific frequency in a fixed point. Waves at the speed of light pass through the cables. Electrons are not transferred, they only vibrate around a fixed point passing their vibration to the next electron. This is how a wave is formed with crests and troughs in quick movement.​
The current that changes its polarity regularly over time is alternating current. Use the following table to contrast the advantages and disadvantages of the types of current. Use this information as fun fact to elicit how much students know about the topic. Did you know​
? The "War of Currents" originated between Nikola Tesla (Westinghouse Electric) and Thomas Alva Edison Activity 2 (General Electric). Tesla defended AC, while Edison was for DC Learning Activity The following activity will help your students reinforce the concepts related to electric current. Match the devices of alternating current and direct current. Images of: a lantern, a fan, a blender, a cell phone, a washing machine and a laptop. Answer key: Direct current: fan, lantern and washing machine. This box contains devices that are directly connected to the electric network of our homes. Direct current: lantern (uses batteries), laptop and cell phone because rectifiers must be used to change the network's alternating current into direct current. The following skills are developed in this activity: Multimedia, infographics, games Skill 3. SKILL 3: Prove Ohm's law. Skill 4. SKILL 4: Interpret diagrams of series and parallel electric circuits, and make an electrical drawing of their home or classroom. Present the concept of voltage and its power supplies. Use the image for a historical overview about the topic. Voltage To maintain electric current we need something that allows the continuous movement of charge. This is called potential difference or voltage, that is, the energy per unit of charge given by the power supply to move electrons from the positive to the negative pole. The unit of measurement is Volt, equivalent to joule per coulomb. Voltage power supplies: devices that generate a potential difference to produce an electric current. Next figure shows the voltaic battery made of small silver and zinc disks separated by a cardboard disk covered in a saline solution (electrolyte). Volta's battery. Scheme of the first battery invented by Alessandro Volta Other voltage power supplies are: • Batteries • Rechargeable batteries • Alternators Raise awareness among students on recycling batteries at authorized places. This is a website link where you can find a recycling point near your home or school. https://www.pilascolombia.com/puntos_recoleccion​
#! Very important.​
When batteries have no charge, they must be put in special collection places. When they are deposited anywhere, the environment can be contaminated. In this section, work on the concept of electric resistance and its relation to the length and thickness of cables. Use the graphic as support to explain the concept. Resistance Physical magnitude that allows measuring the difficulty to pass a current through a material. Resistance (R) is measured in ohms (Ω) and depends on the length (L) and cross­sectional area (A) of the wire (cable) where current passes. Where ρ represents the material resistivity, which is a constant value that can be tabulated. The following figure shows four cables of different length and cross­sectional area. Based on the equation above, we can conclude that resistance is directly proportional to the length and inversely proportional to the cross­sectional area of the conductive cable. Consequently, the blue cable has the highest resistance as it is longer and thinner, next are the yellow and red cables with the same resistance, and finally the green cable with the lowest resistance. It is important to highlight how students should use extension cords appropriately. Very important​
. Electric extension cords are for temporary use only. They must be used no longer than 4 hours, since they tend to heat up due to their high resistance and may start fires. Next, explain Ohm's Law using the animation as support. It can be useful for students to interact with the magnitudes involved. Ohm's Law The voltage (V) applied to a wire is directly proportional to the generated current. Resistance is the constant value of proportionality. It is shown in the following equation. V = I x R This animation (​
go to http://www.educaplus.org/game/ley­de­ohm​
) allows modifying the values of voltage and resistance. When the circuit is closed, we observe that: When the voltage increases, with a fixed resistance, current increases. When the resistance increases, with a fixed voltage, current decreases. When the resistance and voltage increase in the same proportion, current level remains the same. Electric circuits An electric circuit is a set of wires connected to a voltage power supply that keeps the flow of electrons through time. Circuit elements •
•
Voltage power supply: battery or rechargeable battery. Receptor: electric device that consumes energy. •
•
•
Switch: allows interrupting current at your discretion. Connectors: cables that allow connecting the elements. Measuring instruments: allow measuring voltage, current or resistance in the circuit. In this part, provide students with simple examples about connections to bulbs and resistors, so that they make a diagram using electric symbols. Drawing of a circuit We draw connections between elements of the circuit based on their symbology Next, present the characteristics of a series circuit and a parallel circuit. Use the animation as support for students to interact with magnitudes and understand conclusions better. Series circuit Two or more elements of the circuit are in series when they are connected one after another, so each element is part of the circuit. This can be observed in the next figure: Series circuit. There are three resistors R1, R2 and R3 in series connection, one amp meter and one voltage power supply. In the animation (go to http://www.educaplus.org/game/resistencias­en­serie), the value of resistors and applied voltage can vary, so we can conclude that: • The current in the two resistors is always the same, and equal to the total current of the circuit. • The sum of voltages of each resistor is equal to the applied voltage. • The voltage in each resistor is directly proportional to the applied voltage. • The equivalent resistance of the circuit is the sum of the two resistors. It is calculated through this formula Req = R1 + R2 + ... • The higher the equivalent resistance, the lower the current in the circuit. Following the Colombian tradition, people decorate Christmas trees using a lot of lights. These Christmas systems are simply LED lights connected in series, so when a light turns off, the entire series turns off, as well. Parallel circuit Two or more elements of the circuit are in parallel when they are connected from their ends, that is, each element is part of a different division of the circuit. This can be observed in the next figure: Parallel circuit. B1, B2 and B3 in parallel connection, one amp meter and one voltage power supply. In the animation (go to http://www.educaplus.org/game/resistencias­en­paralelo​
), the value of resistors and applied voltage can vary, so we can conclude that: • The current in the two resistors is always the same, and equal to the total current of the circuit. •
•
•
The sum of voltages of each resistor is equal to the applied voltage. The voltage in each resistor is directly proportional to the applied voltage. The equivalent resistance of the circuit is the sum of the two resistors. It is calculated through this formula: •
When the equivalent resistance of the circuit decreases, the total current increases. Colombian homes use parallel circuits in the electric network. As a result, we can turn off a light bulb o appliance and the others continue to be on. These parallel circuits ensure that each electric device has the same amount of voltage from the installed outlets. This activity will help your students reinforce concepts about electric circuits and Ohm's Law. Learning activity 2 Choose True (T) or False (F), as appropriate: 1. In a circuit of two bulbs in series, the voltage given by the power supply is the same for both bulbs. ( ) According to Ohm's Law, the total current of a circuit is inversely proportional to the resistance. ( ) In a circuit with three resistors in parallel, the sum of individual currents of each resistor is equal to the total current of the circuit. ( ) Equivalent resistance increases when more elements are connected to a parallel circuit. ( ) The longer the cable, the lower the resistance to passing current. ( ) Answer key: 1. False. In a series circuit, the voltage given by the power supply is distributed proportionally between both bulbs. True. In a fixed voltage, the higher the resistance of the material, the lower the current passing through the wire. True. The total current of the circuit is divided among the three resistors False. In a parallel circuit, the resistors are added up inversely ,based on this equation: Activity 3 5. False. Resistance in a cable is directly proportional to its length. The following skills are developed in this activity: Skill 5. SKILL 5: Analyze the environmental impact of thermopower and hydropower plants in Colombia. Skill 6. SKILL 6: Carry out research on the losses of energy caused by transport through high voltage lines. SKILL 7: Review studied concepts by practicing with passive voice sentences. The following is a presentation showing how hydropower and thermpower plants work. Animation, Infographcs, Multimedia Use the Infographics as support, progressively showing the step­by­step process of electric power generation. Hydropower plant This facility allows transforming the energy of water movement into electric energy, using turbines connected to generators. Reservoir: mass of water accumulated artificially, generally by diverting the flow of a river. Dam: retaining wall that keeps water accumulated in the reservoir. Valve: allows controlling the intake of water to pipelines. Penstock: directs water to the turbine, taking advantage of the transformation from potential energy into kinetic energy. Turbine: kinetic energy of water makes the turbine blades spin. Its axis is connected to the generator. Generator: transforms the mechanical energy from the spinning blades of the turbine into electric energy. Transformer: converts voltage into an appropriate value for transportation. Electric networks: they transport electric current from the plant to the substations of cities. There are many hydro​
power​
plants in Colombia with high, medium and low capacity to generate energy. The most important include Chivor in Boyaca, Jaguas in Antioquia, and Sogamoso in Santander. Use this information as fun fact to elicit how much students know about the topic. Did you know?​
Colombia generates only 0,11% of its electric energy through wind stations? Thermo​
power​
plant This facility generates electricity from fossil fuels, by means of a thermodynamic cycle of water and vapor. Storage tank: stores the fossil fuel. If the fuel is natural gas, no storage is needed because it comes through gas pipelines. Boiler: combustion is generated in this area to heat up water. Coils: pipelines where heat is exchanged between combustion gases and water, which turns into vapor. Turbines: water vapor makes the blades of turbines spin. Generator: the turbine axis is assembled to the generator, which transforms the mechanical energy of rotation into electric energy. Transformer: converts voltage into an appropriate value for distribution. Electric networks: they transport electric energy. Condenser: cools down vapor to make it liquid and reuse it in a new cycle. Chimney: expels the combustion gases. The fossil fuels commonly used in Colombia are carbon and natural gas, although liquid fuels such as ACPM, fuel oil, and kerosene are also used. Most thermopower plants in Colombia are located in the Coast because its flat surface makes it difficult to build reservoirs for hydroelectric plants. The most important thermoelectric plants of the country include TermoCartagena, Tebsa and Termoflores. In this section students will reflect on the environmental impact of the most used electric plants in Colombia. Environmental impact Thermopower plants: Colombia generates approximately 27.74% of its energy through Thermopower plants. 9.85% of these plants work on gas, 8.20% on carbon and 9.69% on liquid fuels such as ACPM, fuel oil and kerosene. This causes important environmental impacts, for example: • The emission of waste into the atmosphere: the combustion of these fuels generates particles that contaminate air such as carbon dioxide, nitrogen oxides, carbon monoxide, and smaller particles that may contain metals. •
Heat transfer: the condenser of the thermal plant uses river or sea water to cool down vapor. In this process, heat is transferred to the water masses, increasing their temperature. Hydropower plants: 69.97% of Colombia's electric energy is generated through Hydropower plants. Although their production is considered to be clean, their impact on the environment occurs when they are built. Some problems are: • Diversion of the flow of rivers to accumulate water in reservoirs, which can reduce the level of rivers. • Lands are submerged, altering the surrounding area. • The life cycle of some animal species changes around the dam. This part presents the process of electric energy distribution after generation in the plants. Contextualize the topic using the map of electric networks of Colombia. Distribution Networks After the electric energy has been generated in hydropower or thermopower plants, it must be transported to consumers. This process of transmission occurs in three stages: Stage 1. Transmission: from the power plants to the substations. The transmission lines are very long cables, so their resistance is high. To reduce resistance, it is necessary to place very thick cables and increase voltage over 220 kV by means of transformers. This reduces the losses from energy dissipation. Large metal towers able to support the weight of these cables are used for this purpose. Stage 2. Subtransmission: it is necessary to reduce the voltage in the substation to lower values from 34.5 kV to 115 kV, for distribution near houses. Thinner cables and shorter energy posts are used for this purpose. Stage 3. Distribution: there are reduction transformers very near houses to reduce voltage down to a commercial value of 110 V in residential areas, and 220 V in industrial areas. Colombia has approximately 24,400 Km of transmission lines from the electric plants to the substations (Figure 17). Next link shows the electric transmission lines in Colombia. Look for the page #23. http://www.upme.gov.co/Memorias%20Convocatoria%20Red
es%20de%20Alto%20Voltaje/UPME_Alberto_Rodriguez.pdf Remind students about the units of voltage measurement and explain the units of current and resistance. Remember that... the Kilovolt (kV) is a unit of Voltage measurement equivalent to one thousand volts. The following is the activity for this section, which will help students understand better the concepts about electric power generation in hydroelectric and thermoelectric plants. Learning activity 3 Drag the concepts of the left column with the content of the right column. To do this, drag the concept over the match definition. A generator =transforms mechanical energy intro electric energy. A turbine = transforms kinetic energy into mechanical energy of rotation A transformer = increases voltage to a value appropriate for distribution. Most of the electric plants in Colombia are = Hydropower plants. LANGUAGE PRACTICE Fill in the blanks with the appropriate verb from the box. These passive voice sentences will help you review some studied concepts: Abstract Abstract Generate/Create/Form/Use 1. Electrons are not transferred, they only vibrate around a fixed point passing their vibration to the next electron. This is how a wave ______________with crests and troughs in quick movement. 2. In electric wires made of materials such as copper or aluminum, current _______________by the movement of electrons of negative charge. 3. 69.97% of Colombia's electric energy _________________ through hydroelectric plants. 4. Thinner cables and shorter energy posts __________________ for distribution to homes. ANSWER KEY: 1. is formed 2. is created 3. is generated 4. are used Compare your answers with a classmate. For example: Student A: What do you have for number 1? Student B: I have.. The following is a summary of the studied contents presented as a mind map. Homework H​
omework The following activity involves Skills 3 and 4, and allows going in detail about the concepts of Ohm's Law and its application to series and parallel electric circuits. Students must have reviewed and understood the contents presented in Activity 2 to do this exercise. It is important to plan the execution times for this homework. It can be developed in the classroom or at home. 1. In groups of 3, analyze the electric devices of your classroom. 2. Make a list of all the electric elements found in your classroom. 3. Draw a scheme of the electric connection of these devices in your notebooks. 4. Now, draw an electric diagram (with symbols) of this circuit in a poster. 5. Socialize with your classmates through a presentation of works and compare with the other groups. 6. Evaluation Evaluation The following evaluation is suggested as a review of the concepts studied in this LO. You must review each activity, understand the suggested resources and develop the learning activities presented. Place the elements of each electric plant, and the elements they share: Table and answer key: Choose the correct option in each case: 1. Camilo has an extension cord to connect the computer to an outlet far from his workstation. After a while, Camilo sees that the cord is heating up; this occurs because: A. Resistance is higher B. Voltage is lower C. Current is interrupted D. The computer is broken. A parallel circuit contains two identical resistors of 10 Ω each. The equivalent resistance of the circuit is: A. 10 Ω
B. 20 Ω
C. 0,1 Ω
D. 5 Ω If 9V are applied to a circuit, and the wire has a 2 Ω resistor, the value in amperes of the current generated in the circuit is: A. 18
B. 4,5
C. 11
D. 7 Select the right term according its meaning: Voltage/Current/Resistance/Series/Ohm 1. Energy per unit of charge, measured in Volts____ 2. Flow of electrons through a wire, as a result of potential difference._____ 3. Contrary to the movement of electrons in a wire____ 4. Electric circuit where all the elements receive the same current.____ 5. Scientist who formulated the relationship among voltage, current and resistance._____ Answer Key Section II 1A. Resistance is directly proportional to length. 2D. Equivalent resistance is equal to: 1Req=110+110=15→Req=5 3B. According to Ohm's law: I=VR=92=4,5 Section III Voltage: potential difference applied to the ends of a wire. Current: depends on the number of electrons moving through a wire in the time unit. Resistance: determines the opposition to the flow of electrons. Series: all the elements are connected one after another. Glossary Glossary Vocabulary box Vocabulary box Ohm: formulated the law to relate V, I and R. Alternator: generator of alternating current. It creates electric current by means of magnetic fields. Ampere: unit to measure current. It is expressed as the amount of charge passing a cross­sectional section of a wire in the time unit. Combustion: chemical reaction of oxidation, where large amounts of energy are emitted as heat. Wire: material that allows passing electric currents. Photocell: electronic device that transforms light Into electric current. Polarity: property of some objects to accumulate charge in opposite points. English Review topic: ​
Passive Voice Appliance​
: A device or piece of equipment designed to perform a specific task: electrical and gas appliances Retrieved on May 26 from: http://www.oxforddictionaries.com/ Rule of thumb:​
a method of procedure based on experience and common sense. Retrieved on May 26 from: http://www.merriam­webster.com/dictionary Light Bulb​
: a rounded glass container with a thin thread of metal inside that produces light when an electric current goes through it. Retrieved on May 26 from: http://dictionary.cambridge.org/ Cross­section:​
a view or drawing that shows what the inside of something looks like after a cut has been made across it. Resistor​
: a device that is used to control the flow of electricity in an electric circuit. Retrieved on May 26 from: http://www.merriam­webster.com/dictionary. Troughs​
: a low point in a regular series of high and low points: Investing small amounts regularly is a good way of smoothing out the peaks and troughs of the stock market. Wire​
: (a piece of) thin metal thread with a layer of plastic around it, used for carrying electric current: Someone had cut the phone wires.Retrieved on May 26 from: ​
http://dictionary.cambridge.org/ Bibliography Bibliography Castañeda, H. (1991).​
Hola Física Grado 11.​
Medellín: Susaeta ediciones. Cidead. (2010).​
Física y Química. Fenómenos y circuitos eléctricos.​
Retrieved from: http://recursostic.educacion.es/newton/web/materiales_didacticos/EDAD_3es
o_fenomenos_y_circuitos_electricos/3quincena11/3q11_index.htm Cursos y Materiales del MEVyT.​
Ciencias Naturales. Recuperado de http://www.conevyt.org.mx/cursos/cursos/cnaturales_v2/interface/main/recurs
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Portal Educativo Chileno.​
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tenidos_estudiantes_ciencias_fisica/fig%2038.JPG Endesa educa. (2014).​
Generación eléctrica.​
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­de­electricidad/ IES Domingo Miral.​
Electrostática. ​
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terialdeaula/FQ3ESO%20Tema%204%20Propiedades%20electricas%20de%2
0la%20materia/FQ3ESO_Tema_4_Propiedades_electricas_de_la_materia_Re
sumen.pdf OLCA. Observatorio latinoamericano de conflictos ambientales. (2015). Retrieved from: http://olca.cl/articulo/nota.php?id=105441 Cursos y Materiales del MEVyT.​
Ciencias Naturales. Recuperado de http://www.conevyt.org.mx/cursos/cursos/cnaturales_v2/interface/main/recurs
os/antologia/cnant_2_15.htm Romero, O., Rincón, L. (2008).​
Nueva Física 11.​
Bogotá: Santillana. Serway, R.,Jewett, J. (2009).​
Física para ciencias e ingeniería con física moderna.​
Retrieved from: http://datateca.unad.edu.co/contenidos/299010/Carpeta_AVA
/Fisica_2.pdf SIEL.​
Sistema de información eléctrico colombiano​
. Recuperado de http://www.siel.gov.co/siel/Home/Generacion/tabid/56/Default.aspx Unesa Electricidad.​
Funcionamiento de las centrales eléctricas.​
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s/esquemas.htm UN Periódico. (2012). Universidad Nacional.​
Daños ambientales, los pecados de las hidroeléctricas. ​
Retrieved from: http://www.unperiodico.unal.edu.co/dper/article/danos­ambie
ntales­los­pecados­de­las­hidroelectricas.html UPME. Unidad de Planeación Minero Energética. (2015). Informe mensual de variables de generación y del mercado eléctrico colombiano Diciembre 2015. ​
Retrieved from: http://www.siel.gov.co/portals/0/generacion/2015/Seguimien
to_Variables_Diciembre_2015.pdf UPME. Unidad de Planeación Minero Energética. (2013). Sistema de Transmisión Nacional Eléctrico Colombiano. Retrieved from: http://www.upme.gov.co/Memorias%20Convocatoria%20Red
es%20de%20Alto%20Voltaje/UPME_Alberto_Rodriguez.pdf Wikimedia Commons.​
Pila voltaica.​
Retrieved from: https://commons.wikimedia.org/wiki/File:Pila_voltaica.svg