Ingrid Munson & Meghan Campbell. Overview Expectations Safety Considerations Prior Knowledge ...

Ingrid Munson & Meghan Campbell

Overview

Grade 9 Physics

Characteristics of Electricity

Where does series and parallel circuits fit into the unit? Throughout the unit, students gain an understanding of

basic electricity through a study of static and current electricity.

Using a variety of instruments and tools, students develop skills relating to the achievement chart.

They use their knowledge and understandings of the relationships among current/electrical resistance/ potential difference, and energy/power/time to solve simple problems.

A culminating task could include the student applying their knowledge to design and construct an electrical circuit that performs a specific function.

During the unit they will evaluate social, economic, and environmental costs and benefits associated with electrical energy production and distribution in Canada.

Teaching Strategies

Today, our strategies include an interactive game and an inquiry investigation.

Other teaching strategies include website resources and other various labs.

Overall Expectations

Design and conduct investigations into electrical circuits found in everyday life and into the quantitative relationships among current, potential difference and resistance.

Specific Expectations Describe the potential difference and current

characteristics in a series and a parallelcircuit;

Compare the electrical resistance of a seriesand a parallel connection of identical resistorsto that of a single resistor

Demonstrate the skills required to planand conduct an inquiry into electricity,using instruments, tools, and apparatussafely, accurately, and effectively (e.g.,use an ammeter and a voltmeter tomeasure current and potential differencein a circuit);

Goals of Lesson

Construct circuits and review prior knowledge of series and parallel circuits

Learn how to use ammeters and voltmeters safely to make various readings in different types of circuits using light bulbs

Safety Students are to be instructed in a safe and proper

operation of electrical equipment, especially equipment involving voltages over 24 V (individual human tolerance varies greatly);

Only CSA approved electrical equipment should be used; Equipment should be checked to ensure connections are

tight and that there are no damaged or loose wires; All electrical circuitry must be checked by the teacher

before the switch is closed where there is the possibility of harm to students or damage to electrical equipment;

Students should be warned that dry cells may explode if shorted out (short circuited);

Safety Wires which short circuit dry cells become

extremely hot and may cause burns when touched, or fires if in contact with flammables.

The STAO web site at http://www.stao.org/safety.htm has information on safety publications, articles from Crucible and links to other safety sites.

The teacher reinforces safety cautions noted by students from their earlier years. Stress should be on personal safety and the appropriate use of equipment.

Prior Knowledge Students have some background knowledge of

electricity from their Grade 6 Science and Technology program. They are familiar with terms such as load, source, switch, conductor, insulator and parallel and series circuit.

Diagnosis of prior learning should continue throughout the content of this unit. Students have developed inquiry skills - both research and experimentation - in previous units, andalso have gained experience in several different modes of communication (e.g., oral presentation, several forms of written reports, demonstration using concrete materials, diagrams, use of models, etc.).

Circuit diagrams Minimum Three elements:

-Source of electricity (battery)

-Path or conductor on which electricity flows (wire)

-Electrical resistor (lamp) which is any device that requires electricity to operate

Pictorial way of showing circuitsThis is the Ammeter symbol

This is the Voltmeter symbol.

This is the resistor symbol.

This is the switch symbol.

This is the battery symbol.

Series Circuit

Closed electrical circuit that is connected so that the current passes through each circuit element in turn without branching off.

Race Track

Parallel Circuits•Have more than one path that the circuit can follow and electrical energy therefore is not shared.•Each electrical device can be on or off within the circuit.

Parallel CircuitsCars have many pathways to travel, one might be a five lane freeway,

while another is a two lane street. Eventually all cars must return to the service station for more energy.

Game

http://www.planetscience.com/sciteach/index.html?page=/under11s/playground/playground.html

Current Electricity Lab

Pre-lab talk See lab handout

Debriefing http://physics.bu.edu/py106/notes/Circuits.html http://www.allaboutcircuits.com/vol_1/chpt_5/1

.html http://www.iit.edu/~s http://www.ndt-ed.org/EducationResources/Hi

ghSchool/Electricity/seriesparallelcircuits.htm mile/ph9113.html

http://www.bbc.co.uk/schools/gcsebitesize/physics/electricity/circuitsandamme

http://www.autoshop101.com/trainmodules/elec_circuits/circ120.html tersrev3.shtml

Misconceptions/Challenges Depending on students prior knowledge from the grade 6

curriculum, students may be at different stages of their learning with this concept

Definitions will need to be reviewed to ensure scientific language is used -terms such as  parallel difference, Ohms, load, source, series circuit, parallel circuit, current

Basic rules of schematic circuit diagrams (rectangular in nature; correct symbols for components)

Students may confuse the difference between ammeter and voltmeter in terms of what each measures

It is difficult for the teacher to explain this concept when students cannot actually see it for themselves. This is why circuit diagrams are so useful.

Resources

The following Internet sites contain information from Ontario Hydro onsafety codes and the Ontario power generation system:http://www.esainspection.net/main.htmlhttp://www.ontariopowergeneration.comThe site below lists energy information for common applianceshttp://energuide.nrcan.gc.ca/

Resources The same information is available in the

book EnerGuide, available from various hydro offices.

The Office of Energy Efficiency of Natural Resources Canada c/o Canada Communication Group, Ottawa, ON K1A 0S9 has publications such as Air Conditioning Your Home; Household Lighting; Comparing Heating Costs; How Can Energy-efficient Appliances Save You Money?

Follow Up

Concepts to follow would include:-resistance

-electrical energy production-static electricity-simple home circuits

Helpful Websites

http://www.csupomona.edu/~apfelzer/demos/resistor/ser-par/10-ser.html

http://www.tryengineering.org/lessons/elecswitch.pdf

Exit Pass

Often the actual values of the current and potential difference are not exactly the same as the predicted theoretical values. What are two assumptions that are made when we make predictions about these values?