MARY WARD CATHOLIC SECONDARY SCHOOL
Centre for Self-Directed Learning
Grade 9 Academic Science (SNC 1D1)
Unit # 10: Physics – Characteristics of Electricity
Static Electricity
Unit Last Revised: November 2013
ACTIVITY DESCRIPTION
TIME
EVALUATION
CATEGORY
MARKS
Rubric
Knowledge/
Inquiry
Level
Activity A - Static Electricity
1. Electrostatics – the study of
static electricity
1.5 hr
Activity B – Charging Objects
1.
2.
3.
4.
Friction
Contact
Induction
Attraction to neutral objects
Activity C – Unit Assessment
Total Activity Time:
2.0 hr
2.5 hr
6.0 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 electrical
circuits.
 Demonstrate an understanding of the principles of static and current electricity.
Understanding Basic Concepts
 Explain the characteristics of conductors and insulators and how materials allow static charge to build up or be
discharged.
 Compare and contrast static electricity with alternating current (AC) and direct current (DC). (e.g., the charge on
a charged electroscope, the charge in a functioning circuit).
Developing Skills of Investigation and Communication
 Conduct investigations into the transfer of static electric charges by friction, contact, and induction, and produce
labeled diagrams to explain the results.
 Predict the ability of different materials to hold or transfer electric charges (i.e., to act as insulators or
conductors), and test their predictions through inquiry.
Page 2 of 18
Activity A – Static Electricity
1. Electrostatics – The study of static electricity
Although the term “electrostatics” may not be that old, the electrostatic phenomenon has been studied ever
since the early Greeks. It is thought that the Greek philosopher, Thales, studied the attraction between fur and
amber when the two were rubbed together. Ever since then, this type of attraction has been known as the
“amber” effect. In the late 1500s, William Gilbert found that other materials also showed this effect and coined
the term ‘elektron effect’ where ‘elektron’ came from the Greek word for amber. Today we are equipped with a
better understanding of electrostatics, and we are able to take advantage of a wide variety of related
technologies – dryer sheets to photocopying.
Electricity is the general term referring to electric charge. Static electricity is this electric charge that is
stationary or “at rest” (static). It is the build-up of an electric charge on an object and can be produced by
rubbing different substances together (Friction). Current electricity (alternating and direct), on the other hand is
the movement of these electric charges through an object – we will look at current electricity in another unit.
Electrostatics is the study of static electricity.
In this activity you will learn about the concepts associated with the study of static electricity. In particular you
will read about electrically charged particles, the movement of electrons, electron affinity, the laws of attraction,
and electrical insulators and conductors
□
□
□
In your Investigating Science 9 textbook read pages 394, 396-401
On the next page is a crossword summarizing the material you just read. Complete this crossword as your
introduction to electrostatics.
Answer the following in your notebook:
1) What does “static” mean in “static electricity”?
2) State the laws of attraction and repulsion.
3a) Define conductor and insulator.
b) In a table, classify two good conductors, two fair conductors, and two insulators.
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STATIC ELECTRICITY CROSSWORD
1
2
4
3
5
6
7
8
10
9
12
13
14
CLUES:
Across
3. Positively charged particles found at the centre of the atom.
8. A material that does not allow charges to move freely through an object.
9. What like charges do.
10. A metal used in electrical cords. This metal is a good conductor of electricity.
12. If an atom has more protons than electrons, it has a ___________ charge.
13. Negatively charged particles surrounding the nucleus.
14. Neutral particles found in the nucleus of an atom.
Down
1. A material that allows charges to move freely through an object.
2. A conductor directly connected to Earth.
4. Electric charge that builds up on the surface of an object.
5. If an atom has more electrons than protons, it has a ___________ charge.
6. According to the law of attraction and repulsion, unlike charges __________.
7. Having no electrical charge
11. The study of static electricity.
Page 4 of 18
11
Activity B – Charging Objects
There are 3 main ways to build up stationary charges (static electricity) on objects. These are by friction, contact (touch)
and induction. In the next section you will compare these methods by looking at the kinds of charges you start with and
the kind of charges you end up with. In order to understand how these work, you must remember some rules:
1. ONLY ELECTRONS MOVE FROM ONE OBJECT TO ANOTHER, PROTONS DO NOT MOVE!
2. OPPOSITE CHARGES ATTRACT
3. SIMILAR CHARGES REPEL
1. CHARGE BY FRICTION
Friction is the force resisting the relative motion of two surfaces in contact with each other. The rubbing of the
surface of one object on that of another causes this friction. The force of friction can remove electrons from one
object and cause them to transfer to the other object. As one object loses electrons, the other object gains them.
Then, because they are oppositely charged, they attract each other. See Table 1, and Figure 1.
HOW IT HAPPENS:
START WITH
Two neutral objects.
Table 1
TRANSFER ELECTRONS
One object loses electrons, the other
gains them.
END WITH
One positive, the other negative.
They attract.
1. BEFORE friction:
+–+–+
– +– + –
– +– +– +–+– +– +
A neutral ebonite rod has 6 positive
charges and 6 negative charges.
A neutral cotton cloth has
5 positive charges and 5 negative charges.
2. DURING friction:
–+ –+ –+ –+ – + –+
+–+–+
– +– + –
When the rod is rubbed by the cotton
cloth, ELECTRONS move from the
cotton to the ebonite rod.
They attract
3. AFTER friction:
+ +–+–
++–
– +– +– –+ –+– –
+ + – –
Now a negative ebonite rod has 6 positive
charges and 8 negative charges.
Figure 1
Page 5 of 18
The positive cotton cloth has
5 positive charges and 3 negative charges
Activity B – Charging Objects – continued…
□
□
Re-read p.398 of your Investigating Science 9 textbook. Use the chart on this page to answer the following question
in your notebook:
1. In each of the following pairs, state which one is more likely to give up electrons?
a) cotton or ebonite rod (see above)
b) wood or human hair
c) plastic wrap or steel
d) cotton or silk
Friction is the action that causes static in our everyday lives. In your notebook write about one example of creating
charge by friction. Explain what happens because of this build up of charge. You may need to do research for this.
2. CHARGE BY CONTACT OR TOUCH:
Electrons are often transferred from one neutral object to another through friction – there is a force moving them
from one thing to another. Electrons can also be transferred through contact or just by touching a charged object to
a neutral object. In this case the neutral object gains the same type of charge as the object that touched it. The end
result is two similarly charged objects. See Table 2 and Figure 2.
REMEMBER ONLY ELECTRONS MOVE!
HOW IT HAPPENS:
START WITH
One charged object and one neutral
object.
Table 2
TRANSFER ELECTRONS
The electrons move from the
negatively charged object to the
neutral one.
1. BEFORE contact:
– +– +– +–+
Neutral ebonite rod
END WITH
Both objects have the same charge.
If the original charged object was
negative, both will now be negative. If
the original was positively charged, both
the objects will be positive. They repel.
2. DURING contact:
– –+
– – –
– +– +– +–+
– –+
– – –
Negatively charged
steel sphere
Electrons move (not protons) from
sphere to rod, as they are attracted to
the protons in the rod.
3. AFTER contact:
They repel
– +
– –
– +– +– +–+
– –
Ebonite rod is now
negative
Steel sphere remains
negative.
Figure 2
Page 6 of 18
Activity B – Charging Objects – continued…
□
□
□
Read p. 404, and 406-407 of your Investigating Science 9 textbook.
Note what a metal leaf electroscope looks like – we will be using one of these later in the unit.
Using the template below – Figure 3, draw and fill in the blanks to explain what happens when a positive sphere
touches a neutral rod. Again, remember, only electrons move. Use Figure 2 to help guide you.
After contact:
The rod is ____________________ and the sphere is ____________________
1. BEFORE contact:
– +– +– +–+
Neutral rod
2. DURING contact:
+ + +
+ – +
+
Positively charged
steel sphere
+
+
+
+
__________ move (not protons) from
________________as they are attracted
to the_____________ in the ___________.
They ________
3. AFTER contact:
+
+
+ + +
+ +
+ + +
+ +
+
Rod is now
____________
Steel sphere remains
____________.
Figure 3
Page 7 of 18
Activity B – Charging Objects – continued…
3. CHARGE BY INDUCTION:
Induction is the movement of electrons within a substance, caused by a nearby charged object, without
direct contact between the substance and the object. The induced charge is USUALLY a temporary charge
and is only detected as long as the charged object comes close to the neutral one. You can see an example
of this on p. 407 in your textbook, Figure 10.17.
a) An electroscope:
Since an induced charge is mostly temporary, it is difficult to see induction at work unless you have
instrument to show you that the charge exists We often use an electroscope to see that something might
be charged. A metal-leaf electroscope has two very thin metal pieces, called leaves, suspended from a
metal rod – you can see this on p.405 in your textbook, Figure 10.12. When a charge is transferred to the
plate or metal knob, the charges spread out over the whole structure, including the leaves. The leaves are
no longer neutral and both have the same charge so they repel each other. You will be using one of these
during your lab activity in this unit.
b) Grounding
We can actually make an induced charge a permanent charge on an object by grounding that object during
induction. Grounding is the process of connecting a charge object to the Earth’s surface. Grounding
provides a pathway for electrons to travel to and from the ground. As shown in your textbook, p. 408,
Figures 10.18 and 10.19 when the sphere on the electroscope that has an induced positive charge (from
the negative rod) is grounded, electrons will travel to the ground from the electroscope, making it positive.
A ground is essential to charge an object by induction.
To understand charging by induction better, please view the following video on YouTube. It talks about
charging by friction, and charging by induction.
http://www.youtube.com/watch?v=o0hXYfvnND0
In the case of induction, you start with a neutral object and a charged object. Using a ground to transfer electrons,
you end up with two OPPOSITELY charged objects. See Table 3 and Figure 4.
Page 8 of 18
Activity B – Charging Objects – continued…
REMEMBER ONLY ELECTRONS MOVE!
HOW IT HAPPENS:
START WITH
One charged object and one
neutral object.
Table 3
TRANSFER ELECTRONS
The electrons from the charged object
cause the movement of electrons into
one part of the neutral object, causing
a temporary charge on one part of the
neutral object. No electrons move in
or out of the neutral object at this
time.
Adding a ground while the charged
object is still in proximity allows the
electrons to move in or out of the
neutral object. The ground is then
removed and the charged object is
negative or positive.
1. BEFORE induction:
2. DURING induction a):
– –+
– – –
– +– +– +–+
Neutral rod
– +– + +
– –
Negatively charged
sphere
.
+
+
– –+
– – –
Electrons in the rod are repelled from
sphere. There is a temporary “charged
area” on the rod.
3. DURING induction b):
– +– + +
– –
END WITH
The objects have the opposite charges.
If the original object was positively
charged, the neutral object will become
negative. If the original charged object
was negative the neutral object becomes
positive.
– –+
– – –
4. AFTER induction
– –+
– – –
– +– + +
–
Ground
The rod is now POSITIVELY
The sphere
charged.
remains
NEGATIVELY
charged.
Electrons flow out of the rod into the ground.
Figure 4
Page 9 of 18
+
Activity B – Charging Objects – continued…
□
□
Read the bottom of p.407 and p. 408 in your Investigating Science 9 textbook.
Using the template below – Figure 5. Draw and fill in the blanks to explain what happens when a positive sphere
induces a neutral rod. Again, remember, only electrons move. Use Figure 4 to help guide you.
After induction:
The rod becomes ___________________ and the sphere is ____________________.
1. BEFORE induction:
2. DURING induction a):
+ –+
+ + +
– +– +– +–+
Neutral rod
+
Positively charged
sphere
.
+
+
+
+
+ –+
+ + +
+
Electrons in the rod are _________ to the
positive sphere. There is a temporary
“charged area” on the rod.
3. DURING induction b):
+
+
+ –+
+ + +
4. AFTER induction
+ –+
+ + +
+
Ground
+
+
+
The rod is now __________
The sphere
charged.
remains
Electrons flow ______ the rod ______ the ground.
____________
charged.
Figure 5
□
Obtain subject teacher’s signature to check Figure 3 and the fill-in-the-blanks, and Figure 5 and fill in the blanks:
□
 teacher signature:__________________________________
If you don’t understand, charge by friction, contact and/or induction please ask your teacher for a
seminar. There are probably others who don’t understand either.
Page 10 of 18
Activity B – Charging Objects – continued…
4. Attraction and Neutral Objects:
The last thing about charging and charged objects you should know is that neutral objects are attracted to
charged objects. This occurs because of the temporary charge that occurs by induction. When a charged
object is brought close to a neutral object, the electrons are either attracted to or repelled from the charged
object. They do no leave the neutral object but they do move within the object, creating a temporary
“charged area” in the neutral object (see Figure 4, part 2). The neutral object is now attracted to the charged
object. The following diagram (Figure 6) shows what happens using a negatively charged object.
– +– + +
– –
`
+
– –+
– – –
Electrons in the rod are repelled from
sphere. There is a temporary “charged
area” on the rod. The positives are now
attracted to the negatives in the sphere.
Figure 6
Page 11 of 18
The neutral rod is
attracted to the negative
sphere.
Page 12 of 18
Activity C – 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
Knowledge
Minimal knowledge of
facts, terms, concepts,
theories and relationships
was demonstrated.
Level 2
Some knowledge of facts,
terms, concepts, theories
and relationships was
demonstrated
.
Level 3
Level 4
Adequate knowledge of
facts, terms, concepts,
theories and relationships
was demonstrated
Thorough knowledge of
facts, terms, concepts,
theories and relationships
was demonstrated
1) What is static electricity?
2) What are the 3 ways we can generate static electricity? Describe each in detail.
3) What does it mean when an object is electrically neutral?
Page 13 of 18
4) Why do neutral objects get attracted to charged objects? Use a diagram to support your answer.
5) What is the difference between materials that are conductors and insulators? Give examples.
6) Using the Triboelelectric series, identify which objects in the table below lose
electrons and gain electrons when rubbed together.
Remember, objects that lose electrons become positively charged and objects that
gain electrons become negatively charged.
Object that becomes
negatively charged
Object with becomes
positive charged
Plastic rubbed with fur
Glass rod rubbed with silk
Ebonite rubbed with
cotton
Nylon rubbed with wood
Teflon rubbed with steel
Cotton rubbed with hair
Page 14 of 18
Lab – Charging Objects
You do this lab in a group (max 4 students) but will need to hand in an individual report with your unit assessment. Sign
out the following lab kit: Unit 10 – Charging Objects.
Inquiry
Level 1
Level 2
Level 3
Minimal critical thinking
and inquiry skills were
used to interpret data and
form conclusions
Some critical thinking and
inquiry skills were used to
interpret data and form
conclusions
Adequate critical thinking
and inquiry skills were
used to interpret data and
form conclusions
Level 4
Thorough critical thinking
and inquiry skills were
used to affectively
interpret data and form
detailed conclusions
PART A: The Laws of Static Electricity
Purpose: To determine how a charged object behaves towards a neutral object when brought close together, how a
charged object behaves toward a similarly charged object when brought close together and how a charged
object behaves toward a differently charged object when brought close together.
Hypothesis: Make a guess. Before doing the lab, circle the appropriate action is:
1. When a charged object is brought close to a neutral object, I think the neutral object will
a) be attracted to the charged object
b) be repelled by the charged object
c) not be affected by the charged object.
2. When a charged object is brought close to a similarly charged object, I think the similarly charged object will
a) be attracted to the charged object
b) be repelled by the charged object
c) not be affected by the charged object.
3. When a charged object is brought close to a differently charged object, I think the similarly charged object will
a) be attracted to the charged object
b) be repelled by the charged object
c) not be affected by the charged object
Page 15 of 18
Materials and Apparatus: 2 plastic straws
1 glass rod
confetti
plastic bag
watch glass
fur
Procedure:
Trial 1: A plastic straw is rubbed with fur. The negatively charged plastic straw is held close to the neutral paper
confetti. Record your observations in Table 2.
Trial 2: A plastic straw is rubbed with fur. The negatively charged plastic straw is held close to a fine stream of tap
water, which is neutral. Record your observations in Table 2.
Trial 3: A plastic straw is rubbed with fur and mounted on a watch glass (ask the lab room teacher how to do this).
Another plastic straw is rubbed with fur. Both straws are negatively charged. The charged end of this straw is
brought close to the similarly charged end of the straw mounted on the watch glass. Record your observations
in Table 2.
Trial 4: A plastic straw is rubbed with fur and mounted on a watch glass (ask the lab room teacher how to do this).
A glass rod is rubbed with a plastic bag. The straw is negatively charged and the glass rod is positively charged.
The charged end of this glass rod is brought close to the oppositely charged end of the straw mounted on the
watch glass. Record your observations in Table 2.
Table 2
Trial
Object #1
Object #2
1
Straw
(negative charged)
Confetti
(neutral)
2
Straw
(negative charged)
Water
(neutral)
3
Straw
(negative charged)
Straw
(negative charged)
3
Straw
(negatively charged)
Glass Rod
(positively charged)
What happens when objects are brought close to
happen
AFTER COMPLETING THE TABLE, OBTAIN A SIGNATURE FROM THE LAB TEACHER:
TEACHER SIGNATURE: ____________
Conclusion:
1. What happens when a charged object is brought close to a neutral object?
2. What happens when similarly charged two objects are brought close to each other?
3. What happens when oppositely two objects are brought close to each other?
Page 16 of 18
PART B: Charging By Induction – Using an electroscope
Purpose: To use an electroscope and charge it by induction.
Materials and Apparatus: A metal-leaf electroscope – you will get this separately from the dispensary
1 plastic straw
fur
Procedure:
1. Take the plastic straw and rub it in the fur.
2. Bring the straw close to the electroscope, but do not touch it. Notice what happens to the leaves of the electroscope.
Describe what you noticed in Table 1.
3. Take away the straw. Notice what happens to the leaves of the electroscope. Describe what you noticed in Table 1.
4. Re-charge the straw by rubbing it in the fur. Once again, bring the straw close to the electroscope, but do not touch
it. While the straw is close, touch the sphere on the electroscope with one of your fingers. Leave it there. Notice
what happens to the leaves of the electroscope. Describe what you noticed in Table 1.
5. Before removing your finger. Take the straw away. Now take away your finger. Notice what happens to the leaves
in the electroscope. Describe what you noticed in Table 1.
After doing Part B of the lab activity, please take
the electroscope back to the science dispensary to
allow someone else to use it!
Observations:
Action
Straw close to the
electroscope, without
touching it
Take the straw away
Table 1
What you notice about the leaves of the electroscope
Straw close, without
touching it, finger on
sphere
Take away straw, take away
finger
AFTER COMPLETING THE TABLE, OBTAIN A SIGNATURE FROM THE LAB TEACHER:
TEACHER SIGNATURE: ____________
Page 17 of 18
Conclusion:
a) Using a diagram, draw what happens to the charges in the electroscope during steps 4 and 5 of this experiment.
Assume that the straw is negatively charged. Use Figures 10.18 and 10.19 on page 408 in your Investigating 9 Science
to help you to do this.
b) Why did the leaves of the electroscope stay open at the end of the experiment?
c) With regards to electricity, what is a ground? What in this experiment has acted as a ground?
d) Each series of diagrams represents “before,” “during,” and “after.” Match the letter of the series with the correct
situation listed below. Use the diagrams in your guide to help you.
_______ A neutral electroscope is touched by a positively charged rod.
_______ A neutral electroscope is touched by a negatively charged rod.
______ _ A neutral electroscope is approached by a positively charged rod
Congratulations! You have now completed Unit #10.
Page 18 of 18