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MARY WARD CATHOLIC SECONDARY SCHOOL
Centre for Self-Directed Learning
Grade 9 Academic Science (SNC 1D1)
Unit # 11: Physics – Current Electricity
Unit Last Revised: December 2013
ACTIVITY DESCRIPTION
TIME
EVALUATION
CATEGORY
MARKS
Rubric
Knowledge
Level
Activity A - Introduction to Current
Electricity
1. Current Electricity, Circuits,
and Cells
1.0 hr
Activity B – Potential Difference,
Current, and Resistance
1. Potential Difference/Voltage
2. Current
3. Resistance
3.0 hr
Activity C – Circuit Diagrams
1. Circuit Diagrams
2. Series and Parallel Circuits
Activity D - Unit Assessment
Total Activity Time:
2.0 hr
2.0 hr
8.0 hr
Expectations: These are the things you will be learning in this unit:
Overall
 Investigate, through inquiry, various aspects of electricity, including the properties of static and current
electricity, and the quantitative relationships between potential difference, current, and resistance in electric
circuits
 Demonstrate an understanding of the principles of static and current electricity
Understanding Basic Concepts
 Identify electrical quantities, and list their symbols and their corresponding SI units
 Compare and contrast static electricity with alternating current and direct current
 Identify the components of a simple DC circuit and explain their functions
 Explain the characteristics of electric current, potential difference, and resistance in simple series and parallel
circuits, noting how the quantities differ in the two circuits
 Describe, qualitatively, the interrelationships between resistance, potential difference, and electric current
 Explain what different meters measure and how they are connected within an electrical circuit to measure
electrical quantities
 Explain how various factors influence the resistance of an electrical circuit
Developing Skills of Investigation and Communication
 Use appropriate terminology related to electricity
 Design and draw circuit diagrams of series and parallel circuits, and measure electric current, potential
difference, and resistance at various points in the circuits
 Analyse and interpret the effects of adding an identical load in series and in parallel in a simple circuit
 Investigate the quantitative relationships between current, potential difference, and resistance in a simple series
circuit
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Activity A – Introduction to Current Electricity
1. Current Electricity, Circuits, and Cells
In the following unit you will investigate different components of current electricity. Current electricity is the
electricity produced by the continuous flow of electrons (remember only electrons move, protons do not). In
order for this flow to happen we require two things:
1) an energy source – such as a battery or electrochemical cell
2) a complete path – created by connecting wires
Together this forms an electric circuit. Other parts of an electric circuit include loads and switches. Loads are
devices which convert electrical energy into another form of energy, like a light bulb. A switch can turn a circuit
on or off by connecting and disconnecting the circuit.
**make sure to become familiar with the parts of an electric circuit because you will be building circuits in the
next unit**
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in your Investigating Science 9 textbook, read pages 432-436
view the following website (link is on Edmodo):
http://www.energyquest.ca.gov/story/chapter04.html
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as you read, define the following terms in your notebook: circuit, current electricity, load, battery,
electrochemical cell
answer the following in your notebook:
1) What are the two components of an electrochemical cell? Describe their function.
2) What is the difference between a wet cell and a dry cell?
3) Why should dry cells be recycled rather than thrown in the trash?
4) What is a fuel cell?
Page 3 of 10
Activity B – Potential Difference, Current, and Resistance
1. Potential Difference/Voltage
In a battery the electrons gain stored energy, called potential energy. By connecting a wire to the battery the
electrons can then leave by the negative electrode and move through the circuit until it returns to the battery by
the positive electrode.
Throughout the circuit, the potential energy the electron started with has been used for motion or has been
converted to other forms of energy by a load. Therefore, at different points of the circuit there is a difference in
energy which we call the potential difference or voltage. The symbol for voltage is V.
Here’s another way to think of it…
Think of the ski lift as the battery and the skiers as electrons.
The ski lift brings the skiers to the top the hill and at this point
they have a lot of potential energy. As the skier goes down the
ski path (which is like a wire for electrons) the potential energy
is used for motion until the skier reaches the bottom.
Therefore, voltage or potential difference is the difference in
energy that the skier has at different points on the slope.
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in your Investigating Science 9 textbook read pages 437-438
answer the following in your notebook:
1) What does potential difference measure? What is another name for potential difference?
2) What device can we use to measure potential difference?
3) What SI unit is potential difference measured in?
2. Current
Electric current is a measure of the amount of electric charge that passes a point in a circuit each second. So in
the analogy above, current could be the amount of skiers passing a specific tree per second. The symbol for
current is I.
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in your Investigating Science 9 textbook, read pages 439-440
answer the following in your notebook:
1) What are two types of currents? Describe them.
2) What device can we use to measure current?
3) What SI unit is current measured in?
Page 4 of 10
3. Resistance
As the skiers go down the hill there may be some objects that slow them down along the way, for example fallen
skiers, moguls, etc. We can say that these objects are resisting the flow of the skiers. In a circuit, electrons can
also encounter resistance.
Resistance is the degree to which a substance opposes the flow of electric current through it. All substances
resist electron flow to some extent. The symbol for resistance is R.
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in your Investigating Science 9 textbook, read pages 441-443
answer the following in your notebook:
1) What kind of substances has low resistances? What kind of substances has high resistances?
2) What happens to the current when a substance resists the flow of electrons? What is the electrical
energy converted into?
3) What device can we use to measure resistance?
4) What SI unit is resistance measured in?
5) What is a resistor? Give some examples of applications that resistors are used for.
6) Name and describe four factors that can affect the resistance of a wire.
Activity C – Circuit Diagrams
1. Circuit Diagrams
Circuit diagrams use special symbols to represents parts of a circuit. So this
circuit…
is represented by..
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in your Investigating Science 9 textbook, read pages 448-450
in your notebook, copy Table 11.2 Circuit Symbols.
in your notebook, draw a circuit diagram that includes a resistor, a switch, an ammeter and a battery
connected by conducting wires. Show your teacher your circuit diagram to get a signature.
Teacher signature: _________________
Date: ___________
Page 5 of 10
2. Series and Parallel Circuits
The circuits that we have looked at so far are series circuits. A series circuit has only one path for the current to
flow. Components are arranged one after another. If the path is broken the whole circuit cannot function.
A series path is like the ski hill that we saw earlier in this unit guide…
A parallel circuit has more than one path for the current to flow. Since this type of circuit has different paths, an
interruption in one path will not affect the other pathways.
If a ski hill had parallel paths it would look like this…
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in your Investigating Science 9 textbook, read pages 451-452
in your notebook, draw a circuit diagram of a series circuit with a battery, connecting wires, two light bulbs,
and one resistor.
in your notebook, draw a circuit diagram of a parallel circuit with a battery, connecting wires, two light
bulbs, and one resistor. Show your teacher both circuit diagrams to get a signature.
Teacher signature: _________________
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Date: ___________
answer the following in your notebook:
1) Explain why the flow of current is different in series and parallel circuits.
2) Explain why the voltage/potential difference used by loads is different series and parallel circuits.
3) How do combination circuits help prevent problems in circuits in a home?
Page 6 of 10
Activity D – Unit Assessment
 Hand in for assessment: level
After completing all the learning checkboxes, you are now ready to complete your unit assessment. Answer the
following questions and hand in to your teacher. Some questions will be the same as the ones you have already done in
your notebook.
After your teacher reviews your answers, you will receive a unit assessment feedback sheet. You will not get a
numerical mark for this assessment but a level from the rubric below and feedback on where you need to improve.
Level 1
Minimal knowledge of
facts, terms, concepts,
theories and relationships
was demonstrated.
Knowledge
&
Communication Has difficulty in
communicating
information about the
unit.
Level 2
Level 3
Level 4
Some knowledge of facts,
terms, concepts, theories
and relationships was
demonstrated
Adequate knowledge of
facts, terms, concepts,
theories and relationships
was demonstrated
Thorough knowledge of
facts, terms, concepts,
theories and relationships
was demonstrated
Has difficulty
communicating some
information in the unit.
Is able to talk about
learning in all unit
concepts.
Is able to show a high
degree of learning in all
unit concepts.
Introduction to Current Electricity
1) List AND describe the functions of 4 components of an electric circuit.
2) Why should dry cells be recycled rather than thrown in the trash?
Page 7 of 10
Potential Difference, Current, and Resistance
3) What is potential difference? Why would electrons leaving a resistor have less potential energy than when they
entered?
4) What is current? How does increased resistance in a wire affect electrical current?
5) List AND describe four factors that affect resistance in a wire.
Page 8 of 10
Circuit Diagrams
6) Draw the symbols for a battery, a light bulb, a resistor, and a switch in the chart below. Circle the two
components that are types of loads.
Battery
Resistor
Light Bulb
Switch
7) Draw a circuit diagram of a SERIES circuit with a battery, connecting wires, one light bulb, and two resistors.
8) Draw a circuit diagram of a PARALLEL circuit with a battery, connecting wires, one light bulb, and two resistors.
9) Draw a circuit diagram of a SERIES circuit with a battery, connecting wires, one light bulb, and one switch. Now
add a voltmeter in PARALLEL to the light bulb.
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10) Design and draw a circuit diagram where two bulbs can be turned off while one stays on.
Analysis of Voltage and Current in Parallel and Series Circuits
11) Explain why the flow of current is different in series and parallel circuits.
12) Explain why the voltage/potential difference used by loads is different series and parallel circuits.
Congratulations! You have now completed Unit #11.
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