Electrical charges are caused by positive and negative charges from protons and electrons. All objects begin neutral but can become positively or negatively charged by gaining or losing electrons. There are two forces between charged objects - attraction between opposite charges and repulsion between like charges. Charges can be induced through friction, conduction, or induction without direct contact. The triboelectric series ranks materials based on their ability to gain or lose electrons through friction charging.

1. Electrical Charges
Electricity – describes all the
phenomena caused by positive and
negative charges.

2.  All matter has electrical charges
 There are two types of charges:
Positive Protons
Negative Electron
 If you have an equal number of
positives as negatives, makes
neutral
Electrical Charges:
+
-

3. Electrical Charges:
 All objects begin neutral & can become
positively or negatively charged
 A negatively charged object contains
more Electrons than Protons
 A positively charged body contains more
Protons than Electrons

4. Electrical Charge (Q)
 Elementary charge – the charge
carried by a single electron or proton.
It has a value of 1.62 x 10-19
C
 Coulomb (C)– unit of measurement
for electrical charge.
 One coulomb is equal to the charge of
6.25 x 1018
electrons or protons

5. Current Intensity (I)
 Current Intensity (I) is the flow of
charge (Q) per second (t).
 I (Amps) = Q (Coulomb) (C )
 t (seconds) (s)
 E.g. What is the current intensity if
10 C of charge moves in 2 seconds?
 I = Q = 10 C = 5 Amps
 t 2 s

6.  There are 2 forces between charged
objects:
Attraction Repulsion
 Opposite charges
 “Opposites Attract”
 Same charges
 “Like repel”

7. Electrical Forces
 Electrical Force – force at work in
attraction or repulsion
 Law of conservation of charge –
electrical charges can neither be
created nor destroyed only
transferred from one body to
another.

8. Sphere A is negatively charged.
A
When placed beside sphere B, they attract.
What is the charge on B?
-
BA
+
Opposites
Attract!
POSITIVE

9. Three charged spheres are suspended
next to each other.
A B B C
If sphere A is negatively charged,
what will happen when sphere A & C are
suspended beside each other?
A C
Attract

10. Four charged spheres are suspended next
to each other.
A B B C C D
What will happen if A & D were suspended
next to each other?
+ + + - - +
Repel

11. You have three charged
objects – A, B & C in a lab.
You record the following
results:
Test Observation
Bring “A” near “B” They repel
Bring “A” near “C” They attract
What would happen if “B” & “C”
were brought together?
They would attract!!!
+ +
+ -
+ -

12. Electrostatic:
 Static electricity describes all the
phenomena related to electrical charges at
rest. (read pg 145)
 Friction
 Conduction
 Induction

13. Charging by Friction
 When two items are rubbed together, 1
item takes the electrons and the other
item loses the electrons, resulting in 2
different charges on the items! (p.146)

14. Charging by Conduction

15. Charging by Induction
Induction refers to an action that occurs
without direct contact. A charged object is
placed near a neutral object and its
opposite charges tend to move near the
charged object. (p. 147)

16.  Triboelectric series is a list that ranks
objects’ ability to take negative
charges
Triboelectric Series:
Rubber
Ebonite
Polyethylene
Cotton
Silk
Wool
Glass
Acetate
Fur / Hair
Items above
take negatives
Items below
lose negatives
Only negative charges move!
Positive charges NEVER move!!

17. You rub your hair with a balloon. Explain
using words & pictures, why your hair
“sticks up”.
1st
Hair & balloon are
both neutral
2nd
Rubber balloon takes
negative charges from the
hair. So, balloon becomes
negatively charged & hair
becomes positively charged
3rd
Since hair is positive &
like charges repel,
hair sticks up!!!
+
+
++
+
_ _
_
_
_

18. Your cat rubs against a rubber balloon.
What will be the charge on the balloon?
Your cat’s fur?
Rubber
Ebonite
Polyethylene
Cotton
Silk
Wool
Glass
Acetate
Fur / Hair
Rubber
Fur / Hair
Items at top
take negatives
Negatives
Rubber
balloon
becomes
negative
Cat’s fur
becomes
positive

19. In a lab, you take a piece of neutral wool
& neutral polyethylene & rub them
together. What will be their charges?
Rubber
Ebonite
Polyethylene
Cotton
Silk
Wool
Glass
Acetate
Fur / Hair
Wool
Polyethylene
Items at top
take negatives
Negatives
Polyethylene
balloon
becomes
negative
Wool
becomes
positive

20. In a lab, you rub a piece of
cotton & ebonite together.
Then you rub a piece of silk
& wool together.
Rubber
Ebonite
Polyethylene
Cotton
Silk
Wool
Glass
Acetate
Fur / Hair
Cotton is +
Silk is -
They
would
ATTRACT
You then bring the charged piece of
cotton & the charged piece of silk
together. What will happen?
+
-
-
+

21.  Two types of charges – positive (+) &
negative (-)
 “Opposites Attract”
 “Like Repel”
 Items at the top of the triboelectric
series list take negative charges
 Only negative charges move

22. Activities
 Electric Charges Worksheet

23. References
 Student Study Guide – Physical
Science 416/436 - MEQ
 Science Quest – Grenier, Daigle,
Rheaume – 1998, Cheneliere
 Google Images
 Animation Factory