Static Electricity Intro

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