header.gif


Electricity


electricity-wordle.jpg

Resources:

Text Chapter 9
SIMON Learning Areas General Documents

Short Films and quizzes and activities based on these can be found on SIMON
(learning areas -> science year 8 -> electricity)





Week 1

You already know about contact and non-contact forces.
Where does electricity fit in?

VandG.jpeg VandG2.jpeg
Van de Graaff generator.

Week 1 Tasks

1
  • Scientific knowledge changes as new evidence becomes available, and some scientific discoveries have significantly changed people‚Äôs understanding of the world.
  • Model simple, series and parallel circuits.
  • Draw symbols representing components of electrical circuits.
  • Understand and be able to explain properties of conductors, insulators, circuits, switch and resistors.
  • Define key terms: conductors, insulators, circuits, switches and resistors.
  • Draw (model), build and experiment with different circuits (simple, series and parallel).
  • Using circuits diagrams p177
  • Take pictures of complete circuits and include these in your notes.
  • Prac reports in this unit should include a record of the method and an interpretation of data and observations. Why do they think this happened?
  • Students choose which report they will be assessed on. This report may be written more formally
  • Over-to-you exercises p173 (teacher to select) S/N
AusVels-Science-8
SFL08 Ch9 McMillan CSIRO
www.Sjesci.wikispaces.com
Prac template (Wiki/Simon)
Electricity 1,
Circuits 1, WS 1,
Power Grids 1
Resistance 1,

Static Electricity
  • watch short film on SIMON
  • answer quiz
  • Try out the Van der Graaf machine :).

IMG_0968.JPG

Electrical Circuits
  • watch short film on SIMON
  • answer quiz
  • Using circuits diagrams p177
  • Set up and complete prac on BUILDING CIRCUITS (p170)
    • Draw (model), build and experiment with different circuits (simple, series and parallel).
    • Prac Report: structure your report using the template below
    • Record your steps, results and the answers to your questions in Keynote.
    • Define key terms: conductors, insulators, circuits, switches and resistors.
    • Take pictures of complete circuits and include these in your notes.
    • Prac reports in this unit should include a record of the method and an interpretation of data and observations.
    • Why do they think this happened?
  • Over-to-you exercises p173 (teacher to select) S/N

Survey

Concept Map
  • Have an enquiring mind?
  • Like to know how it all fits together?
  • Look at this Xmind
  • Discuss what it means with the person next to you
  • Then create your own Xmind about all the electrical things that you use at home and at school.
  • Colour-code (most to least important to you or your family)


Another Youtube on electricity :)


The following exercise helps to put your thinking in words:
It is based on the 3 questions....
  1. What did you know before?
  2. What have you learned?
  3. What would you like to find out?

Week 2 Tasks

2
  • Energy appears in different forms including movement (kinetic energy), heat and potential energy, and causes change within systems.
  • Measure and explain the difference between current and voltage.
  • Model circuits which allow, observation, recording and interpretation of voltage and current.
  • Understand the structure and function of a simple battery.
  • Provide practical examples and notes explaining current and voltage.
  • Complete one of the following practicals.
  • Measuring current and voltage (part A and B) p179
  • Research the internal structure of a battery.
  • Make a lemon battery (prac p182) (prac CSIRO)
  • Over to you questions p178 (teacher to select) S/N
Current 1,
Voltage 1,
Battery 1, Lemon battery 1, 2
Electrode 1
Electrolyte 1,
LED 1
Future Ideas 1, 2,

Lemon Battery Prac


Open Lemon Battery Prac and write up in Prac Format.
  • Date
  • Title
  • Aim
  • Method:
    • copy "what to do" (section one) but delete parts that refer testing for electrical current using your tongue :).
    • copy "what to do" (section two) but change 'nail' to strip of zinc.
    • add any missing information
      • work in groups of 2 with 2 lemons each.
      • first try and set up a circuit using 1 lemon, then two.
      • Try and measure the volts and amps using volt and Ammeter.
      • Record your results in a table and take a photo at each stage of the method. Include this in your result.
      • Combine groups 4 lemons, then again 8, then again 10 lemons
    • LemonBatteryStepFour.jpeg.

  • Materials: include voltmeter, ammeter, multimeter as well as those things recommended in the prac under 'you will need'.
  • Theory:
  • Results:
Number of lemons in series
Volts
Amps
Brightness of glow on LED globe
2



4



6



8



12




  • Discussionof Results
    • What you were able to see?
    • What did you learn?
    • What could have been done better?
    • What did the prac show?
    • Compare voltage (volts) to current (amps) using this experiment as an example in your explanation.
    • Current research into LED lights, or alternative power sources.
    • How might the electrodes in a pace-maker work?


Discuss results and write up prac.

Notes:
  1. Examples where energy changes from one form to another: Batteries (Chemical > Electrical), Power Stations (Chem > Mechanical > Electrical), Solar (Light > Chem > Electrical).

Week 3 Tasks

3
  • Science and technology contribute to finding solutions to a range of contemporary issues.
  • Measure and control variables, and select equipment to collect data with accuracy
  • Safety features of electrical circuits. (Fuses and circuit breakers)
  • Van der Graaff Generator: can be used to introduce potential and kinetic energy and the earthing process (why most electrical devices have earthing wires).
  • Short circuits and fuses p184
  • Over to you questions p186 (teacher to select) S/N
Van de Graff Generator: 1, 2
Static Electricity: 1, 2
Short circuits 1, 2 Film 1,
Fuses 1, Circuit breaker 2
Earth wires 1

Notes:
Van der Graaff Generator (mechanical > electrical energy). Static electricity builds up till it is able to be released in a sudden discharge to an earthing object. When that object is you, you feel a shock. This sudden charge can actually be enough to damage mobile phones and other electrical equipment. An extreme example of a sudden release of electrical energy in a lightening strike.

Safety Features in Electrical Equipment: To protect electrical equipment and us from the damage caused by too much current (too much electricity) we use fuses / circuit breakers and earthing wires.

Prac: Build and test how a fuse works - Science for Life Year 8 p154
Over-to-you questions: p186 Q: 1,2,3,5,7.

Static Electricity
Van de Graff Generator: 1, 2
Static Electricity: 1, 2

VDGraaf.png staticelec.jpeg lighteningstrike.jpeg



Earth wires
Earth wires 1, 2

earthplug.jpeg homeearthrod.jpeg earthedstove.jpeg earthedappliance.jpeg



Fuses and circuit breakers
Fuses 1, Circuit breaker 2

fusehouse.jpeg circuitbreaker.jpeg circuitbreakerinside.jpeg


Short Circuit - Sheep Analogy
Short circuits 1, 2 Film 1,

One way to understand fuses is to use an analogy with sheep.
  • When a circuit contains a light bulb, the light bulb is like a gate in the sheep paddock.
  • Although all the sheep want to pass through the gate to get to the green grass on the other side, they can only pass through a few at a time.
  • If the fence is missing, they can all go through at once.
  • A short circuit is like a break in the fence which all the sheep run through.
  • When there is a short circuit in an electrical device so many electrons flow through the fuse that it heats up and melts.
  • This protects the device from catching fire (or its components melting) when the current gets too high.

Remember:
  • current is measured in Amps
  • power is measured in Volts

sheepclip.jpegsheepherd.jpeg sheepmob.jpeg

What is the difference between Kinetic and Potential Energy?
Can you identify which forms of energy used in the examples above are kinetic or potential energy? Try and explain your thinking.

Week 4 & 5 Tasks

4
  • Construct and use a range of representations, including graphs, keys and models to represent and analyse patterns, or relationships.
  • Electrical Gadget (skills tester or other approved project). This should be an open ended task. It could involve moving parts, such as electrical motors (from the robotics kits, however these should only be used with 4 x 1.5 V batteries (6V) as we will not be replacing them if they are damaged (power packs at 12V will damage them). A range of ideas can be found in SFL08 e.g. model torch(Over to you, page 173), model electric kettle (Mind tease, page 187), lighthouse, model house, front door bell, burglar alarm, street lights, boom gates, buzzer for quiz show, alarm clock, mousetrap.
  • Marking is to based on the rubric.
  • Over to you questions p181 (teacher to select) S/N
Motors, bulbs, buzzers, 6V light bulbs, low watt LED bulbs.
Future ideas 1,
5
  • Communicate ideas, findings and solutions to problems using scientific language and representations.
  • Complete, present and mark final project.


Assessment:

Prac Reports: Circuits
Notes and Exercises
Quizzes
Skill Tester Game

Materials:
A battery operated door bell, a stiff wire coat hanger, a piece of wood and some insulation tape.


Instructions:
YOUR BUZZER: First find a battery operated buzzer or door bell (These items can often be found in cheap household stores). Do NOT use a mains voltage operated device as you will stand the risk of death through electrocution. A door bell is perfect, as all the wiring is already done and the voltages are normally low and safe. Ensure you choose a device that uses less than 24 Volts. The coat hanger loop and twisted trail simply make a switch that replace the push button switch of the door bell. You should have two wires when you remove the door button. When you touch them together the buzzer should sound! This is a good test before you start.

THE TWISTED LOOPED TRAIL: Take a block of wood and drill two deep holes that are the exact diameter of your coat hanger.
Bend your coat hanger into an interesting shape with loops and twists. Insert each end into the hole so that it is firmly held held in place.
Twist one of the switch wires around one side of the trail. Place plenty of insulating tape on it. This doubles up as a resting place for the loop so ensure that no bare metal is visible other wise your buzzer will keep sounding when not in use! Add the tape to the other side to make another 'Safe' area for the loop to rest.

THE LOOPY LOOPED HANDLE: Using the stiff metal from a coat hanger, form a loop on one side. Attach the other switch wire to the other end by tightly twisting it around and holding in place with insulating tape. Form a handle. At this point it is worth noting that the larger the hoop and shorter the handle length the easier the game will be! Place the hoop over the twisted trail and close up the gap so it cannot be removed. If the metal of the hoop touches the non insulated metal of the trail the buzzer should sound!

Game Play:
The object of the game is to carefully move the handled hoop over the twisted hanger from one end to the other without the buzzer sounding. It takes great skill and a steady hand!