Electrostatics
Textbook Chp 14
What happened
here?
Electric Charges
 Electric Fields
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Topics
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Electric Charge is a physical quantity
Units of charge is Coulomb (C)
It is NOT an object (e.g. an electron)
There are two types of electric charge –
positive charge & negative charge
Note: charge is a scalar quantity, even
though there is positive and negative!
Electric Charges
An object is said to be neutral when it has
equal number of positive and negative
charges (i.e. no net charge)
 An object is said to be positively charged
when it has more positive charges than
negative charges
 An object is said to be negatively charged
when it has more negative charges than
positive charges
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Electric Charges
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[not in syllabus]
Particles which carry charges are called
charge carriers.
The electron is the most common charge
carrier
Aqueous ions are also charge carriers
The charge of an electron is -1.60 x 10-19 C
This number is represented by the symbol
“e”
Electric Charges
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When two objects which have net charge
are brought close together:
They attract each other if their charges
are opposite
They repel each other if their charges are
alike
E.g. electrons and protons attract each
other; electrons repel each other, protons
repel each other
This force of attraction / repulsion is
called an Electric Force
Electric Force
Recall Gravitational Field - a region in
which a mass experiences a force due to
gravitational attraction
 Electric Field is a region in which a charge
experiences a force
 Electric Field Worksheet
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Electric Fields
Quiz