3.  Understand the basic properties of
electric charge.
 Differentiate between conductors and
insulators.
 Distinguish between charging by
contact, charging by induction, and
charging by polarization.

4. Matter is made up of atoms.
+ Proton (positive charge)
–
neutron (neutral)
+
+ +
– electron (negative charge)
– –
atom nucleus

9. Electric charge is quantized.
Charge is measured in coulombs (C).
The fundamental unit of charge, e, is the
magnitude of the charge of a single
electron or proton.
e = 1.602 176 x 10–19 C

11. An electrical conductor is a
material in which charges can
move freely.
An electrical insulator is a
material in which charges
cannot move freely.

13. Relative
+++++  Glass
electro-negativity  Human Hair
++++
ranking for some  Nylon
+++  Silk
common materials ++  Fur
from electron donating +  Aluminum
materials (+, glass) to  Paper
electron accepting -  Cotton
materials (-, teflon) --  Copper
 Rubber
---
 PVC
----  Teflon
-----

14.  Insulators and conductors can be
charged by contact.
 Conductors can be charged by
induction.
 Induction is a process of charging a
conductor by bringing it near another
charged object and grounding the
conductor.

17. A surface charge can
be induced on
insulators by
polarization.
With polarization, the
charges within
individual molecules
are realigned such that
the molecule has a
slight charge
separation.

18. The electric force is
proportional to the
magnitude of each charge
and inversely proportional to
the square of the distance
between them.

20. Two balloons are charged with an
identical quantity and type of
charge:
-6.25 nC. They are held apart at a
separation distance of 61.7 cm.
Determine the magnitude of the
electrical force of repulsion between
them.

21. Two balloons with charges of
+3.37 µC and -8.21 µC attract
each other with a force of
0.0626 Newton. Determine
the separation distance
between the two balloons.

22. Joann has rubbed a balloon with wool to
give it a charge of -1.0 x 10-6 C. She then
acquires a plastic golf tube with a charge
of +4.0 x 10-6 C localized at a given
position. She holds the location of
charge on the plastic golf tube a distance
of 50.0 cm above the balloon.
Determine the electrical force of
attraction between the golf tube and the
balloon.

23. At what distance of separation
must two 1.00-microCoulomb
charges be positioned in order
for the repulsive force between
them to be equivalent to the
weight (on Earth) of a 1.00-kg
mass?

24. A balloon with a charge of 4.0
µC is held a distance of 0.70
m from a second balloon
having the same charge.
Calculate the magnitude of
the repulsive force.