**
It is expected that students will compare series and parallel circuits involving varying resistances, voltages, and currents.**

**Students who have fully met the prescribed learning outcome are able to:**

Define resistance

Draw circuit diagrams using appropriate symbols that are

properly placed

Conduct experiments to:

- measure voltage and current, using appropriate

equipment and units (e.g., volts, amperes)

- determine resistance, using current and voltage data

Perform calculations using Ohm’s Law

For a fixed supply voltage, differentiate qualitatively between

series and parallel circuits in terms of:

- current (may change from resistor to resistor in parallel;

remains the same in series)

- voltage (may change from resistor to resistor in series;

remains the same in parallel)

- total resistance (increases with the number of resistors in

series; decreases in parallel)

photo: hotblack@morguefile

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**RESOURCES:**

Energy and Environment; Voltage; exercise to determine the relationship between voltage, amperage and resistance (Ohm's law)

Parallel and Series Bulbs - worksheets

Electricity and Magnetism, HyperPhysics, Georgia State University

This Interactive module will introduce you to many of the basic concepts involved with Electricity and Magnetism. We will introduce you to static charge, moving charge, voltage, resistance, and current. Magnetism and how it relates to electricity will also be presented.

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PLANNING FOR ASSESSMENT /**ASSESSMENT STRATEGIES**

Ask students “If power supplies give energy

and a voltage increase to charges, what are

devices called that take away energy?”

Students (in groups) will brainstorm and list

objects that take energy from a charge. They will

generalize and call them resistors. Their

observations and definition will be recorded in

their journals. Assess by considering how many

different devices students can come up with.

**............................................................................................................................................**

Display a circuit and show how the

corresponding circuit diagram is drawn,

using standard symbols to show power

supplies or cells connected in series, wires,

resistors, and voltmeters and ammeters

correctly connected.

Have students set up their own circuit following

the circuit diagram presented. Provide assistance

as required. Ask students to

- measure the voltage across a power supply

and current through it for at least five

different voltages and record the data. (they

can increase voltage by adding more cells in

series or changing the setting on the power

supply)

- determine the voltage-current ratio for each

trial and record data in their data table

If they are able, they should measure the

resistance of the resistor using an ohmmeter.

Have students examine their data to see what is

constant and draw conclusions. Assess whether

- they conduct the set up carefully

- provide accurate data and diagrams

- draw conclusions that correspond to the

substance of Ohm’s Law

Provide help with the activity and with concept

development as necessary.

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Review Ohm’s Law and units. Demonstrate

several examples of problems involving

Ohm’s Law and including unit prefixes such

as milli, mega and kilo.

Students complete Ohm’s Law problems and

submit for marking. Award marks for proper use

of units and showing work, as well as obtaining

correct results.

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Demonstrate for students

- 1, 2 and 3 resistors connected in series and

parallel (keep the terminal voltage

constant throughout)

- the proper use of voltmeters and

ammeters in these circuits (voltage and

current are measured in each circuit and

across each resistor and power supply)

• Have students, working in groups, draw

diagrams of each of the circuits demonstrated.

Have students record the terminal voltage, the

voltage across each resistor, and the current

through each resistor. Verify for accuracy.

• When assessing student work, look for their

ability to

- identify patterns in their data

- state what happens to current, and voltage in

the circuits and how they changed (or did not

change) in each series and parallel circuit

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Follow up by using Ohm’s Law to calculate

total resistance in the circuit using the

terminal voltage and the current readings

from the power supply.

• Students should recognize that

- in a series circuit, the total resistance has

increased as resistors have been added in

series

- in a parallel circuit resistance has decreased as

resistors have been added in parallel

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