Electricity

Concept 1: Conductors, Insulators & Electrical Safety

Success Criteria

  • I can describe what electricity is (movement of electrical charge such as electrons in wires).

  • I can explain how conductors and insulators work.

  • I can list the dangers of electricity, and describe the rules of electrical safety.

  • I can describe the use of circuit breakers, fuses, and residual current devices (RCDs) in electrical safety.

Vocabulary

Energy

Joule

Transformation

Hei Mahi

Hei Mahi: Knowledge Book page 3

Conductors and Insulators of Electricity

Success Criteria:
I can describe what electricity is (movement of electrical charge such as electrons in wires).
I can explain how conductors and insulators work.

What is Electricity?

Electricity is a type of energy that is caused by electrons either building up in one place, or flowing from one place to another.

Conductors and Insulators

Conductors and insulators have different properties when it comes to allowing the flow of electricity because of the way their atoms are bonded together.

Conductors are materials that let electricity flow through them. Most metals are good conductors, such as copper, silver, gold, and aluminium.

The atomic structure of a conductor has free electrons that are able to jump between the atoms that make up the conductor. When a voltage is applied across the conductor, the free electrons jump between each atom and knock into each other in the process. This flow of electrons through the wire is the flow of electric current.

On the other hand, insulators do not allow electricity to flow at all. This is because their atoms have tightly bound electrons. The electrons are not free to jump between neighbouring atoms.

Examples of conductors are plastic and rubber.

Hei Mahi

Hei Mahi: Knowledge Book page 6

Electrical Safety

Success Criteria:
I can list the dangers of electricity, and describe the rules of electrical safety.
I can describe the use of circuit breakers, fuses, and residual current devices (RCDs) in electrical safety.

There are many safety rules that must be followed to stay safe around and when using electricity.

  1. Don’t overload sockets or multi-boards and don’t use too many extension cords. Too many can cause too much current to be drawn and the wires heat up and cause a fire.

  2. Use your ears - a fizzing sound may indicate that there is a short circuit or a loose wire. Turn the socket off and unplug the appliance. Don’t use the socket until it has been fixed by an electrician.

  3. Don’t use exposed or frayed wires. If the plastic coating of a wire is broken or you can see wires do not use the appliance or charger. Once unplugged, cut the cord (so no body else can use it again) and throw it away. Then buy a new one or get an electrician to replace it.

  4. When using anything electrical outside or near water you must use an RCD. An RCD is a residual current device. Its function is to break the circuit and stop you from getting an electric shock.

  5. Keep appliances away from water and never use an appliance in the bath or when wet.

  6. Make your house child proof by covering sockets with special plastic protectors.

  7. Never stick anything metal into a socket or appliance. If the toast is stuck in the toaster, turn it off at the wall and use and plastic spoon or wooden chopsticks to get the toast out.

  8. Check before you dig or climb. There are many overhead and underground cables/wires around. So before you dig check with the “Before U Dig” website for the location of underground cables. When setting up and climbing a ladder check to see if there are any overhead cables in the area.

(Watch the Circuit Breaker video from 0:00 to 1:00).

Task 1: Knowledge Book

  • Page 4 - Vocabulary match-up

  • Page 4 - Knowledge questions

  • Page 5 - Using knowledge (practical investigation)

  • Page 7 - Vocabulary scramble and using these words to write a sentence.

  • Page 7 - Knowledge questions

  • Page 8 - Using knowledge

Task 2: Education Perfect

Do the Education Perfect task called "Concept 1: Conductors, Insulators & Electrical Safety"

Electricity KB pg 3-8 Conductors, insulators, electrical safety.pdf

Concept 2: Static Electricity

Success Criteria

  • I can describe what electricity is, and distinguish between static and current electricity.

  • I can explain how objects can become charged, and apply this to how lightning is created.

  • I can describe what current is in an electrical circuit.

Vocabulary

Energy

Joule

Transformation

Hei Mahi - What is electricity?

Hei Mahi: Knowledge Book page 10

Hei Mahi - How does a Van de Graaff generate static electricity?

Hei Mahi: Knowledge Book page 14

Electricity can be separated into two different types; static electricity and current (or flowing) electricity. Static means “to stay still”. Current is the movement of charge through a conductor such as a wire.

To understand electricity you need to know something about the structure of atoms. In the centre of an atom (the nucleus) are positively charged protons and neutral neutrons that have no charge. Moving around the nucleus are negatively charged electrons.

Static Electricity

Success Criteria:
I can describe what electricity is, and distinguish between static and current electricity.
I can explain how objects can become charged, and apply this to how lightning is created.

When two insulating materials rub together, one material can transfer electrons to the other.

The material that gains electrons becomes more negatively charged.

The material that loses electrons becomes more positively charged.

Van de Graaff Generator

A classic example of generating more significant amounts of static electricity in the Physics Lab is a Van de Graaff Generator, invented by Robert Van De Graaff, an American Physicist.

The Van de Graaf generator can produce and store large amounts of charge to create static electricity.

An electric motor attached to a roller at the base of the Van de Graaf generator causes movement of a wide rubber belt over a piece of felt, which is insulated. The Friction between the moving belt and the felt “strips away” the negative electrons.

The electrons are then passed from the belt to the metal dome which begins to build up a static charge. Because the dome is a conductor the charge spreads out evenly across the dome.

When a person places their hand on the generator the dome will release its charge through the person to get to the ground.

However, if they are standing on an insulating surface (such as plastic chair), the charge cannot go through the body and get to the ground, so the person also will start to become charged.

A person can get a shock from a Van de Graaff if they touch the dome after the generator has been turned on. The charge will jump from the dome to the person. It will be seen as a spark moving from the dome to the person.

How a Van de Graaf generator works

What causes lightning?

When I held the earth wand close to (but not touching) the Van de Graaff generator you might have seen a small spark jump across the gap between the two metal spheres. This is called electrical discharge in air (or... a spark).

Electric discharge describes any flow of electric charge through a gas, liquid or solid. If there are enough positive (+) electrical charges on one object or material and enough negative (−) charges on the surface of the other object the attraction between the charges may be great enough to cause electrons to jump the air gap between the objects. When charges move we call it a current.

Once a few electrons start to move across the gap, they heat up the air, encouraging more electrons to jump across the gap. This heats the air even more. It happens rapidly and the air gets so hot that it glows for a short time. If it is short lived, it is called a spark, if it lasts for a while it is called an arc.

A rough estimate of the amount of voltage based on the size of the spark is approximately 3000 V per mm. So if the spark between the Van de Graaff dome and the earth ball is 5cm, this would mean that the voltage on the dome was approximately 150,000V.

The same thing happens with lightning, except on a much larger and much more dramatic scale, with higher voltages and current.

Task 1: Knowledge Book

Part 1

  • Page 11 - Static electricity vocabulary match-up

  • Page 11 - Static electricity knowledge questions

  • Page 12 - Using knowledge of static electricity

  • Page 15 - Van de Graaff vocabulary match-up

  • Page 15 - Van de Graaff knowledge questions

  • Page 16 - Using knowledge of Van de Graaff generator

Part 2

  • Page 18 - Research, paraphrasing, and vocabulary.

Electricity KB pg 10-16 Static electricity, Van De Graaf generator.pdf
Electricity KB pg 17-18 Static electricity + Lightning.pdf

Task 2: Education Perfect

Do the Education Perfect task called "Concept 2: Static Electricity"

Task 4: PhET Simulation

Explore the PhET simulation below. Use the example of the woolen jumper and balloon to explain static electricity.

Concept 3: Current Electricity

Hei Mahi - What is current electricity?

Hei Mahi: Knowledge Book page 20

Current Electricity

Success Criteria:
I can describe what electricity is, and distinguish between static and current electricity.
I can describe what current is in an electrical circuit.

Current electricity is when electrons continuously flow from one place to another.

It occurs when negatively charged electrons move through a conductor from an area which is negatively charged to an area which is positively charged.

A circuit must be closed, with no gaps, for the charge to flow and produce a current (flow of charge).

Task 1: Knowledge Book

  • Page 21 - Vocabulary word find

  • Page 21 - Current electricity knowledge questions

  • Page 22 - Using knowledge of current

Task 2: Education Perfect

Do the Education Perfect task called "Concept 3: Current Electricity"

Electricity KB pg 20-22 Electric current as a flow of electrons.pdf

Task 3: PhET Simulation

Create a circuit with the biggest amount of current flowing through it!

Concept 4: Electrical Circuits

Success Criteria

  • I can list a range of electrical power sources (DC power supply, batteries).

  • I can correctly draw the symbols of electrical components.

  • I can follow the rules for drawing simple circuit diagrams.

Vocabulary

Energy

Joule

Transformation

Hei Mahi - What is a circuit?

Hei Mahi: Knowledge Book page 24

Circuit Diagrams

Success Criteria:
I can follow the rules for drawing simple circuit diagrams.

When we draw diagrams of circuits, it is important to use specific rules and conventions, as this means that anyone can use and understand the diagram to build the circuit.

These symbols can be used universally by electricians and scientists, regardless of the languages they speak, to show how different circuits are arranged.

A circuit can be as simple as a battery connected to a light bulb, or the very complicated circuit boards inside computers and mobile phones.

The rules for circuit diagrams are:

  • A ruler must be used when drawing circuit diagrams to create neat, straight lines to represent wire.

  • Components should always be drawn in the middle of a section of wire, not on corners.

  • The diagram should have 90° corners.

  • There should be no gaps in the wires.

  • Circuit symbols should always be used.

Circuit symbols are used to represent components of an electrical circuit. Components are all the parts that make up a circuit and carry out a function.

Electrical Components

Success Criteria:
I can list a range of electrical power sources (DC power supply, batteries).
I can correctly draw the symbols of electrical components.

An electrical circuit is a path through which an electrical current flows.

  • The path may be closed (joined at both ends), making it a loop.

  • It may also be an open circuit where the electron flow is cut short because the path is broken. An open circuit doesn’t allow electrical current to flow.

Electrical circuits have several components:

  • Switches can be open (creates a gap in the circuit) and closed (the pathways complete).

  • Lamps are lightbulbs that turn electrical energy into heat and light energy.

  • Voltmeters measure the voltage in places in the circuit.

  • Ammeters measure the current in a circuit.

  • A resistor reduces the flow of electrons (current) in a circuit.

  • A variable resistor is an adjustable resistor which can vary the amount of current in a circuit.

Below are three different ways of representing the same circuit: an image, a circuit diagram and in words:

Task 1: Knowledge Book

  • Page 25 - Vocabulary

  • Page 25 - Circuit diagram knowledge questions

  • Page 26 - Using knowledge of circuit diagrams

Electricity KB pg 24-26 Circuits, symbols, drawing circuits.pdf

Task 2: Education Perfect

  • Do the Education Perfect task called "Concept 4: Electrical Circuits"

Task 3: PhET Simulation

  • Change the settings so that you are looking at DRAWINGS of the components.

  • Create the circuit pictured above (one cell, connected to one lamp).

  • Use the simulator to create your own circuit drawings. Draw these as circuit diagrams in your book.

Concept 5: Series & Parallel Circuits

Success Criteria

  • I can describe series and parallel circuits.

  • I can explain the advantages and disadvantages of series and parallel circuits.

  • I can describe the uses of parallel circuits in everyday life.

Vocabulary

Energy

Joule

Transformation

Hei Mahi - Are there different types of circuits?

Hei Mahi: Knowledge Book page 28

Series Circuits

Success Criteria:
I can describe series and parallel circuits.
I can explain the advantages and disadvantages of series and parallel circuits.

There 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 circuit.

  • If there are branches it's a parallel circuit.

Watch this video to see real series and parallel circuits.

In a series circuit, components connected one after the other.

If you follow the circuit diagram, you should pass through all the different components, without any branches.

Below: A circuit with a battery and two bulbs connected in series.

… BUT if a lamp breaks, or a component is disconnected, the circuit is broken and ALL the components stop working.

Parallel Circuits

Success Criteria:
I can describe series and parallel circuits.
I can explain the advantages and disadvantages of series and parallel circuits.

I can describe the uses of parallel circuits in everyday life.

In a parallel circuit, different components connected on different branches of wire.

If you follow the circuit diagram, you can only pass through all the different components if you follow all the branches.

… AND if a lamp breaks, or a component is disconnected, the components on DIFFERENT branches keep working.

Task 1: Knowledge Book

  • Page 29 - Vocabulary crossword

  • Page 29 - Types of circuits knowledge questions

  • Page 30 - Using knowledge of different types of circuits.

Task 2: Education Perfect

Do the Education Perfect task called "Concept 5: Series & Parallel Circuits"

Electricity KB pg 28-30 Series + Parallel Circuits.pdf

Concept 6: Current

Success Criteria

  • I can describe what current is, and give its symbol and units.

  • I can correctly measure current using a multimeter and ammeter.

  • I can describe and calculate current in series and parallel circuits.

Vocabulary

Energy

Joule

Transformation

Hei Mahi - How can current be measured?

Hei Mahi: Knowledge Book page 32

What is Current and How is it Measured?

Success Criteria:
I can describe what current is, and give its symbol and units.
I can correctly measure current using a multimeter and ammeter.

The flow of electrons along a circuit is known as a current. The symbol for current is I.

Current (I) is measured using an ammeter. The symbol for an ammeter is:

The units for current is amperes (A).

An ammeter is basically an electron counter, that measures the flow rate of charge.

Because of this, ammeters are always connected in series.

Current in Series and Parallel Circuits

Success Criteria:
I can describe and calculate current in series and parallel circuits.

Task 1: Knowledge Book

  • Page 33 - Vocabulary word scramble

  • Page 33 - Current knowledge questions

  • Page 34 - Using knowledge of current

Task 2: Education Perfect

Do the Education Perfect task called "Concept 6: Current"

Electricity KB pg 32-35 Current.pdf

Concept 7: Voltage

Success Criteria

  • I can describe what voltage is, and give its symbol and units.

  • I can correctly measure voltage using a multimeter and voltmeter.

  • I can describe and calculate voltage in series and parallel circuits.

Vocabulary

Energy

Joule

Transformation

Hei Mahi - How can voltage be measured?

Hei Mahi: Knowledge Book page 36

What is Voltage and How is it Measured?

Success Criteria:
I can describe what
voltage is, and give its symbol and units.
I can correctly measure
voltage using a multimeter and voltmeter.

An electric current will not flow through a circuit unless there is a battery or power source to provide energy to the electric charges within the circuit.

‘Potential difference' is a measure of how much energy the electric charges have between two points in a circuit. Potential difference is also known as voltage, symbol V.

Potential Difference (voltage) can be measured with a voltmeter with the units volts, V. A voltmeter must be connected in parallel to a component.

Voltage in Series and Parallel Circuits

Success Criteria:
I can describe and calculate
voltage in series and parallel circuits.

Task 1: Knowledge Book

  • Page 37 - Vocabulary used in a sentence

  • Page 37 - Voltage knowledge questions

Task 2: Education Perfect

Do the Education Perfect task called "Concept 7: Voltage"

Electricity KB pg 36-38 Voltage.pdf

Concept 8: Resistance

Success Criteria

  • I can describe what resistance is, and give its symbol and units.

  • I can describe the effect of resistance in a circuit.

Vocabulary

Energy

Joule

Transformation

Hei Mahi - What is Resistance?

Hei Mahi: Knowledge Book page 39

What is Resistance?

Success Criteria:
I can describe what
resistance is, and give its symbol and units.

Resistance (symbol R) measures how difficult it is for current to move through a component. Resistance is measured in Ohms (symbol Ω)

A resistor in a series circuit will reduce the amount of current that flows through a circuit for any given voltage. Resistors are used to regulate the flow of current in a circuit.

However, any component in a circuit that “uses” energy is a kind of resistor because it is more difficult for current to move through them. Components that add resistance to a circuit often transform electrical energy into light, sound or heat energy, e.g. the thin filament wire in an incandescent light bulb.

Very good conductors like gold, silver and copper have a very low resistance, compared to poor conductors like graphite which has a higher resistance. Insulators are on the opposite end of the continuum. For example air and rubber have a very, VERY high resistance.

Task 1: Knowledge Book

  • Page 40 - Vocabulary match-up

  • Page 40 - Resistance knowledge questions

  • Page 41 - Using knowledge of resistance

Task 2: Education Perfect

Do the Education Perfect task called "Concept 8: Resistance"

Electricity KB pg 39-41 Resistance.pdf

Concept 9: Power

Success Criteria

  • I can describe what power is, and give its symbol and units.

  • I can describe and compare renewable and non-renewable ways of generating electricity

  • I can describe ways of reducing electricity usage.

  • I can describe how power generation in NZ and the National Grid.

Vocabulary

Energy

Joule

Transformation

Hei Mahi - What is Power?

Hei Mahi: Knowledge Book page 45

What is Power?

Success Criteria:
I can describe what power is, and give its symbol and units.

Power is the rate at which the electrical energy is transformed into other forms of energy.

The brightness of a bulb is a measure of the power used by the bulb. The amount of power is determined by both the voltage across the bulb and the current flowing through it.

Power is measured by the unit Watts (W) which is the same as 1 joule of energy used in 1 second. Another way of thinking about power, is the amount of energy something uses per second, or the rate at which energy is used.

How is Power generated in NZ?

Success Criteria:
I can describe and compare renewable and non-renewable ways of generating electricity.
I can describe ways of reducing electricity usage.
I can describe how power generation in NZ and the National Grid.

Task 1: Knowledge Book

  • Page 46 - Vocabulary match-up

  • Page 46 - Using knowledge of power

  • Page 50 - Electricity Supply in New Zealand (Knowledge Questions)

  • Page 51 - Using knowledge of generating power.

Task 2: Education Perfect

Do the Education Perfect task called "Concept 9: Power"

Electricity KB pg 45-53 Power.pdf