FRICTION,
CONDUCTION AND
INDUCTION
How do you charge an object?
• There are three ways to charge an object:
1. Charge by Friction
2. Charge by Conduction
3. Charge by Induction
How do you measure “charge”
• The unit of measure for electrical charge is the
Coulomb (C). In equations it is symbolized by a
“q”
• Eg: q = 900C
• One Coulomb is equal to the charge of 6.25 X 1018
electrons (-) or protons (+).
• That is to say, one Coulomb has 6.25 X 1018
electrons.
Charging Objects
• Most objects start out electrically neutral, but by
CHARGING an object you create an imbalance in the
number of electrons and protons; the object is then
charged and is either positive or negative.
• You can charge an object through:
• Friction – the transfer of electrons from one object to the other
• Conduction – by having two objects TOUCH each other and
transfer electrons from one object to the next.
• Induction – By inducing electrons to move from one object to the
other.
Charging by Friction
• When two neutral objects are rubbed against each other,
one object may pull electrons away from the other
creating one positive object and one negative object.
Electrostatic Series:

All objects begin neutral & can
positively or negatively charged
become

A positively charged object has more
positives than negatives

A negatively charged object has more
negatives than positives
Electrostatic Series:
• Electrostatic series is a list that ranks objects’
ability to take negative charges
Rubber
Ebonite
Polyethylene
Cotton
Silk
Wool
Glass
Acetate
Fur / Hair
Items at top
take negatives
Items at bottom
lose negatives
Items at top
take negatives
Your cat rubs against a rubber balloon. What will
be the charge on the balloon? Your cat’s fur?
Rubber
Rubber
Ebonite
Polyethylene
Cotton
Silk
Wool
Glass
Acetate
Fur / /
Hair
Fur
Hair
Rubber
balloon
becomes
negative
Negatives
Cat’s fur
becomes
positive
Items at top
take negatives
In a lab, you take a piece of neutral wool & neutral
polyethylene & rub them together. What will be their
charges?
Rubber
Ebonite
Polyethylene
Polyethylene
Cotton
Silk
Negatives
Wool
Wool
Glass
Acetate
Fur / Hair
Polyethylene
balloon
becomes
negative
Wool
becomes
positive
In a lab, you rub a piece of cotton &
ebonite together. Then you rub a piece
of silk & wool together.
You then bring the charged piece of
cotton & the charged piece of silk
together. What will happen?
+
+
Rubber
Ebonite
Polyethylene
Cotton
Silk
Wool
Glass
Acetate
Fur / Hair
Cotton is +
Silk is
-
They
would
ATTRACT
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!!!
_
+_ _
+ +
_+ + _
Charging by Conduction
• An object can be charged by touching it with another
object that already has a charge. The resulting object will
then have the same charge but weaker in strength than
the original object.
Charging by Conduction
• This image shows how a positive charged object
alters the charge on the globe via conduction.
Charging by Conduction
• This image shows how a negative charged object
alters the charge on the globe via conduction
Charging by Induction
• Objects do not touch (one is charged, one is neutral)
• Proximity of the charged object causes (induces) the
charges in the neutral object to separate.
Charging by Induction
• This image shows how a negative charged object
alters the charge on the globe via induction.
Charging by Induction
• This image shows how a positive charged object
alters the charge on the globe via induction.
• Two types of charges – positive (+) &
negative (-)
• “Opposites Attract”
• “Like Repel”
• Items at the top of the electrostatic series
list take negative charges
• Only negative charges move
• Three methods to charge an object:
friction, conduction, induction. These three
methods are what cause static
electricity.