# ELECTRICITY UNIT

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ELECTRICITY UNITSCIENCE AND TECHNOLGY- CYCLE 3NAMEGROUPTeacher: Mr. D. Strina E-mail: [email protected] CAIG ELEMENTARY SCHOOL

CLASS NOTES--AtomAn atom is the smallest particle characterizing anelement. All matter in the universe is made up ofa combination of different atoms. Atoms are madeup of protons, neutrons and electrons.Electrical chargeAn electrical charge is produced when an atom losesor gains an electron. When there are more electronsthan protons, the charge is negative. When thereare fewer electrons than protons, the charge ispositive. The unit of electrical charge is the coulomb(symbol: C).Electrical currentAn electrical current is the movement of negativeelectrical charges (electrons) through a conductor(electrical wire, metal foil, etc.). In an electrical circuit,the current flows from the point where the electricalpotential is highest to the point where it is lowest.Electrical circuitAn electrical circuit is the complete loop throughwhich an electrical current flows. It is made up ofa series of electrical components and conductors(e.g., batteries, electrical wires, light bulbs, etc.).The current only flows in an electrical circuit whenthe path is completely closed, forming a loop.1

Types of electrical circuitThere are two types of electrical circuit, parallelcircuits and series circuits. Parallel circuits provideseveral different paths for the electrical current.Series circuits force the current through a singlepath; in other words, the electricity flows throughall the electrical components of a series circuit oneafter the other.Conductors of electricityConductors are bodies or materials that allow anelectrical current to pass through them. Copper,aluminum, brass, zinc, iron and pewter are examplesof metal that conduct electricity well. Salt water isalso a good conductor.ResistanceResistance is the part of an electrical circuit that resiststhe flow of electricity (for example, by transformingit into heat or light, as in a light bulb or a buzz er).In an electrical circuit, the presence of a resistor limitsthe current and prevents damage related to shortcircuits. The unit used to measure resistance is theohm (symbol: Ω).AmpereThe ampere (symbol: A) is the unit used to measurecurrent intensity.2

VoltageVoltage (symbol: V) is the unit used to measureelectrical tension, also called “difference of electricalpotential.”Short circuitA short circuit occurs when two live (i.e., carryingcurrent) conductors accidentally come into contact,either directly or through a conducting object (e.g.,when the blade of an electric lawn mower cuts theelectrical wire). When this happens, the current canflow with very little restriction because the resistanceof the loop formed by the two conductors is very weak.The high amount of current heats up the wires andcan cause a fire. Fuses and circuit breakers detectunusually high currents and break the circuit, whichhelps to prevent fires.BatteryBatteries are reserves of chemical energy that canbe transformed into electrical energy. Small electriccells (commonly called batteries, as in AA batteries)are examples of simple batteries for everyday use.InsulatorInsulators, such as wood and plastic, are materialsthat do not easily transmit heat, cold or electricity.Electrical wires are covered with an insulator toprevent electrical shocks and short circuits that couldcause fires.3

PeopleThomas Alva Edison (1847-1931), a U.S.inventor who designed the first electric light bulb.He also invented many other devices, includingthe phonograph, ancestor of the gramophone.Alessandro Volta (1745-1827), an Italian physicist,invented the first electric battery.4

1STAPLESTAPLEAC M EName:////////Electricity from the wall outlets inyour house powers your television,computer, lights, and microwave.Cell phones, flashlights, and evena car’s headlights are powered bythe electricity in batteries.Super Teacher Worksheets - www.superteacherworksheets.comSuper Teacher Worksheets - www.superteacherworksheets.com23lightcircuit boxswitchwireThe type of electricity that is used topower things we use is called currentelectricity. Current electricity iselectricity that flows through wires.The path that electricity follows iscalled a circuit.5Super Teacher Worksheets - e picture above shows a circuit.Electricity flows from the negativeside of a battery, through the wires,and lights the bulb. The electricitycontinues to travel around to thepositive side of the battery.Draw arrows on the picture to showthe path of the electricity.Super Teacher Worksheets - www.superteacherworksheets.com

Something that uses some of theelectricity in a circuit is called aresistor. Resistors could also be thingslike light bulbs, motors or speakers.STAPLE5A circuit can be open or closed.When a circuit is closed, it is completeand there is no break in the path thatthe charges must follow. When acircuit is open, it is incomplete andcharges can’t flow through.Super Teacher Worksheets - www.superteacherworksheets.comSuper Teacher Worksheets - www.superteacherworksheets.com67STAPLEColor the resistors in the circuit above.Label the two circuits above with thewords “open circuit” and “closedcircuit.”STAPLESTAPLE4A switch is sometimes added to acircuit. The switch opens and closesa circuit to turn resistors on and off.Label the two circuits above with thewords “series circuit” or “parallelcircuit.”Color the switch in the circuit above.Super Teacher Worksheets - www.superteacherworksheets.comIn a series circuit, electricity canfollow only one path. In a parallelcircuit, electricity has more than onepath to follow.6Super Teacher Worksheets - www.superteacherworksheets.com

Name:ElectricityChoose the best answer for each question. Write the letter on the line.1.2.What supplies energy in an electric circuit?a. a conductorb. light bulbc. a wired. a batteryWhich material is a conductor?a. plasticb. silverc. glassd. woodCircuit A3.4.5.Which type of circuit is Circuit A?a. seriesb. parallelc. perpendiculard. currentWhich item is a resistor in Circuit B?a. light bulbb. wirec. batteryd. screwsCircuit BWhy did the person who made Circuit A probably connect the wires to a penny?a. They needed to use a penny to make the bulb light.b. They were testing to see if the penny conducts electricity.c. They used the penny to supply extra power.d. The penny will prevent sparks.6.Which of these could be used as a resistor in a circuit?a. a pencilb. a gas enginec. a rubber eraserd. an electric motor8Super Teacher Worksheets -www.superteacherworksheets.com

Name:Electrical ChargesIf an object has more positive charges ()than negative charges (), its electricalcharge is positive ().If an object has more negative charges (than positive charges (), its electricalcharge is negative ().Example:)If an object has the same number of positive() and negative () charges, it has noelectrical charge or is neutral.Electrical charge: positive chargeCount the positive and negative charges in each picture. Write positive charge,negative charge, or no charge on each line.1.2.electrical charge:electrical charge:3.4.electrical charge:electrical charge:5.6.electrical charge:electrical charge:9Super Teacher Worksheets - www.superteacherworksheets.com

Name:Static ElectricityRubbing a balloon with wool cloth will create static electricity charges.In Picture 1, does the balloon have a positive charge, negative charge, or no charge?In Picture 1, does the cloth have a positive charge, negative charge, or no charge?In Picture 2, does the balloon have a positive charge, negative charge, or no charge?In Picture 2, does the cloth have a positive charge, negative charge, or no charge?If you place small pieces of tissue paper near the balloon in Picture 2, they would probably stick to theballoon. Explain why.Super Teacher Worksheets -www.superteacherworksheets.com10

CircuitsA circuit always needs a power source, such as a battery,with wires connected to both the positive ( )and negative (-) ends. A battery is also known as a cell.A circuit can also contain other electrical components, suchas bulbs, buzzers or motors, which allow electricity to passthrough.Electricity will only travel around a circuit that is complete.That means it has no gaps.Incomplete circuitComplete circuitSymbolsWe use these symbols to draw diagrams of circuits:20

SwitchesWhen a switch is open (off), there is a gap in the circuit.Electricity can not travel around the circuit.When a switch is closed (on), it makes the circuitcomplete. Electricity can travel around the circuit.Switch open (off). Bulb doesn't light.Switch closed (on). Bulb lights.21

Changing circuitsAdding more batteries to a simple circuit will increasethe electrical energy, which will make a bulb brighter.More bulbsAdding more bulbs to asimple circuit will make thebulbs dimmer.Longer wiresLengthening the wires in a simplecircuit will make the bulb dimmer.22

Electrical circuits - Quiz1. In a simple series circuit, why does the bulb light when you close the switch?a-Because the switch produces electricityb-Because closing the switch completes the circuitc-Because closing the switch breaks the circuit2. In a simple series circuit, why does the bulb go out when you open the switch?a-Because the battery goes flat b-Because opening the switch breaks the circuitc-Because too much electricity flows through the bulb3. Imagine a simple series circuit with one 1.5V battery and one bulb. When the1.5V battery is replaced with a 3V battery .A- the bulb gets brighter b- the bulb gets dimmerc-the bulb stays at the same level of brightness4. Imagine a circuit with a 1.5V battery and one bulb. Imagine a similar circuit with a3V battery and two bulbs. Which has the brightest bulbs?a-The circuit with a 1.5V battery and one bulbb-The circuit with a 3V battery and two bulbsc-The bulbs in both circuits are of similar brightness levels5. Why might a bulb flash and go out when a 1.5V battery and a 3V battery are bothconnected across it in a simple series circuit?a-There is not enough electricity flowing around the circuitb-Too much electricity flows through the bulb's filament and the bulb blowsc-The batteries are flat6. What is the effect of changing the wire in a circuit from a straight thick wire to astraight thin wire?a-The bulbs become dimmer b-The bulbs become brighterc-The bulbs stay at the same level of brightness7. What is the effect of changing the wire in a circuit from a straight thick wire to alonger (coiled) thick wire?a-The bulbs become dimmerb-The bulbs become brighterc-The bulbs stay at the same level of brightness8. In a circuit diagram, what does a circle with a cross inside it represent?a-A light bulbb- A motor c- A battery9. What do the long straight lines represent in a circuit diagram?a-Motorsb-Light bulbs c- Wires10. How is a battery represented in a circuit diagram?a-A circle with a cross inside it b- A circle with an M inside itc-A long line and a short line23

Series & parallel circuitsThere are two types of circuit we can make,called series and parallel.The components in a circuit are joined by wires.if there are no branches then it's a series circuitif there are branches it's a parallel circuitSeries circuitsIn a television series, you get several episodes, one after the other. Aseries circuit is similar. You get several components one after the other.If you follow the circuit diagram from one side of the cell to the other,you should pass through all the different components, one after theother, without any branches.If you put more lamps into a series circuit, the lamps will be dimmer thanbefore.In a series circuit, if a lamp breaks or a component is disconnected, thecircuit is broken and all the components stop working.Series circuits are useful if you want awarning that one of the components in thecircuit has failed. They also use less wiringthan parallel circuits.23

Parallel circuitsIn parallel circuits differentcomponents are connected ondifferent branches of the wire. Ifyou follow the circuit diagramfrom one side of the cell to theother, you can only pass throughall the different components ifyou follow all the branches.In a parallel circuit, if a lampbreaks or a component isdisconnected from oneparallel wire, thecomponents on differentbranches keep working.And, unlike a series circuit,the lamps stay bright if youadd more lamps in parallel.Parallel circuits are useful if you want everything towork, even if one component has failed. This is whyour homes are wired up with parallel circuits.24

Name:Series and Parallel CircuitsIn a series circuit electric current has only one path to follow. All parts are connected one afteranother. Electric current flows from the negative side of the battery around in aloop to the positive side.Draw arrows to show the path of electric current in this series circuit.If a light bulb is missing or broken in a series circuit, will the other bulb light? Explain.In a parallel circuit, electric current has more than one path to follow. The electric currentcan follow different paths as it flows from the negative side of the battery to the positiveside.Draw arrows to show the different paths electric current can travel in this parallel circuit.If a light bulb is missing or broken in a parallel circuit, will the other bulb light? Explain.Super Teacher Worksheets -www.superteacherworksheets.com11

Name:Electrical CircuitsTell whether the light bulb or bulbs will light or will not light based on the circuit.1.2.3.4.5.6.12Super Teacher Worksheets - www.superteacherworksheets.com

Name:Series & Parallel CircuitsTell whether each picture shows a series circuit or parallel 13Super Teacher Worksheets - www.superteacherworksheets.com

Name:What's Wrong With These Circuits?1. Explain why the light bulbs won't light in the circuitpictured on the right.2. Explain why the light bulb isn't lighting up in the circuitpictured on the right.3. Explain why the light bulb isn't lighting up in the circuitpictured on the right.Super Teacher Worksheets -www.superteacherworksheets.com14

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Electrical conductors –IntroductionElectricity travels easily through electrical conductors, likemetals.Materials that do not let electricity pass through them easilyare called electrical insulators. Plastic, wood, glass and rubberare good electrical insulators.Electrical conductorsSome materials let electricity pass through them easily. These materialsare known as electrical conductors.Many metals, such as copper, iron and steel, are good electricalconductors. That is why the parts of electrical objects that need to letelectricity pass through are always made of metal.Metal is used in plugs to allow electricity to transfer from the wall socket,through the plug, and into a device such as a radio or TV.In a light bulb, the metal filament conducts electricity and causes the lightbulb to light up.17

Electrical insulatorsSome materials do not allow electricity to pass throughthem. These materials are known as electrical insulators.Plastic, wood, glass and rubber are good electricalinsulators. That is why they are used to cover materialsthat carry electricity.The plastic covering that surrounds wires is an electricalinsulator. It stops you from getting an electrical shock.18

Electrical conductors – Quiz– Circle the best answer1. A material that lets electricity pass through it is called .a-an electrical conductor b-an electrical insulator c- an electrical appliance2. A material that does NOT let electricity pass through it is called .a-an electrical conductor b- an electrical insulator d-an electrical appliance3 .Which of the following materials is an electrical conductor?a-Silver b- Silver-coloured plasticc-Cork4. Which of the following materials is an electrical insulator?a-Aluminumb-Gold c- Rubber5. In which circuit will the bulb or bulbs glow brightest?a-A simple circuit with one bulb and one batteryb-A simple circuit with one bulb and two batteriesc-A simple circuit with two bulbs and one battery6. Why is a bulb brighter when it is powered by two batteries rather than one?a-Because the flow of electricity in the circuit is lessb-Because the flow of electricity in the circuit is the samec-Because the flow of electricity in the circuit is greater7. Ruby has connected two bulbs across two batteries in a simple circuit. How canshe make the bulbs dimmer?a-Replace one of the batteries with a section of wireb-Replace one of the batteries with a corkc-Replace one of the bulbs with a section of wire8. Ruby makes a complete simple circuit with one bulb and three batteries. The bulblights for an instant and then goes out. Why?a-Not enough electricity flows around the circuitb-Too much electricity flows through the bulb's filamentc-The batteries are flat9. Why is electrical wiring usually made from copper?a-Because copper is shiny b- Because copper conducts electricityc-Because copper is not magnetic10. Why is electrical wiring usually covered with a layer of plastic?a-To make it look prettyb-To help electricity flow along the wirec-To make it safe19

Name:Conductors and InsulatorsA conductor is a material that allows electricity to flow through it.An insulator is a material that electricity cannot flow through.To determine whether an object is a conductor or insulator, you can build a simplecircuit with a battery, light bulb, and three pieces of wire.Touch the free ends of the wire to the object you are testing. If the light bulb lights up, theobject is made from a conductor. if it does not, the object is made from an insulator.Complete the table. Predict whether each item is made from a material that is a conductor orinsulator. Then test each item to determine if it is made from a conductor or insulator.ObjectPrediction: Conductor or Insulator?Result: Conductor or Insulator?rubber bandpennynickeltoothpickkeypaper clipbrass paper fastenerglass microscope slide(your choice)(your choice)Super Teacher Worksheets -www.superteacherworksheets.com15

ectric lverChose the best word(s) from the word box to complete each sentence.1.The flow of electricity is an .2.A path that an electric current follows is a .3.A supplies energy to move electricity through a circuit.4.are materials that electrical current cannot pass through.5.are materials that electrical current can easily pass through.6.and are examples ofmaterials that are conductors.7.and are examples ofmaterials that are insulators.8.A is a material that cuts down the flow of current, butdoes not stop it.9.A circuit is a circuit in which electrical current can followonly one path.10.A circuit is a circuit in which electrical current has morethan one path to follow.Super Teacher Worksheets -www.superteacherworksheets.com16

Non Renewable ResourcesNon-renewableWe get energy from many different types of energy resources, includingfuels, food and stores of energy such as batteries or the wind. We candivide energy resources into two categories: nonrenewable and renewable.Non-renewable energy resources cannot be replaced once they are allused up.Renewable energy resources can be replaced, and will not run out.On the this page we'll look at non-renewable resources.Coal, oil and natural gas are called fossilfuels. They formed millions of years agofrom the remains of living things. Coal wasformed from plants. Oil and natural gas wereformed from sea creatures.The energy stored in the fossil fuels originally came from sunlight. Plants usedlight energy from the Sun for photosynthesi

positive. The unit of electrical charge is the coulomb (symbol: C). Electrical current An electrical current is the movement of negative electrical charges (electrons) through a conductor (electrical wire, metal foil, etc.). In an electrical circuit, the current flows from the point where the electrical potential is highest to the point where .

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