This lesson adds further detail to the first lesson on static electricity.

1. Charging and
Discharging
Objects

2. • An electroscope is a
device that allows you to
test whether an object is
charged
• The main parts of an
electroscope are a metal
ball, a metal rod and
metal leaves
ElectroscopesElectroscopes
metal ball
metal rod
metal
leaves

3. • The ball, rod and leaves
are all conductors
• Conductors allow
electrons to move easily
through them
ElectroscopesElectroscopes
metal ball
metal rod
metal
leaves

4. ElectroscopesElectroscopes
When the electroscope is
neutral, the leaves stay
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5. ElectroscopesElectroscopes
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When the electroscope is
positively or negatively
charged, the leaves repel
each other (separate)

6. When a neutral object is touched by a
charged object, some of the charge
transfers to the neutral object and the
neutral object becomes charged.
Charging By ContactCharging By Contact
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7. When a negatively charged object
touches a neutral object, electrons move
to the neutral object making it negative
Charging By ContactCharging By Contact
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ebonite rod

8. When a positively charged object touches
a neutral object, electrons move from the
neutral object to the positive object and
make the neutral object positive
Charging By ContactCharging By Contact
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acrylic rod

9. When an insulating material is charged by
contact, the charge stays on the insulator at
the point where it is touched
Charging By ContactCharging By Contact

10. When a conducting material is charged by
contact, the charge spreads out over the
whole surface of the conductor.
Charging By ContactCharging By Contact

11. Induction is the movement of electrons within
a substance, caused by a nearby charged
object, without direct contact
QuickTime™ and a
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InductionInduction

12. If you rub a rubber balloon on your hair,
electrons will transfer from your hair to the
balloon, making the balloon negative
InductionInduction

13. When you bring the
negatively charged
balloon near a neutral
wall, the electrons on
the balloon repel the
negative charges on the
wall, making that part of
the wall positive
InductionInduction
QuickTime™ and a
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14. The balloon is said to
induce a charge on
the wall because it
charges the wall
without contacting it
InductionInduction
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15. Grounding is the
process of connecting a
charged object to the
Earth’s surface
GroundingGrounding
(Symbol for
grounding)

16. When you connect a
charged object to the
ground, you provide a
path for charges to travel
to or from the ground
GroundingGrounding

17. • When you charge an object by
induction, you use a charged object to
induce a charge in a neutral object
• Then you ground the newly charged
object so that it retains the charge
Charging By InductionCharging By Induction

18. Charging By InductionCharging By Induction
Step 1:
When a negatively
charged object comes
near a neutral
electroscope, it repels
the electrons in the
neutral electroscope

19. Charging Permanently
By Induction
Charging Permanently
By Induction
Step 2:
When you ground the
neutral electroscope,
you provide its
electrons with a path
away from the
repulsive influence.
Some electrons leave
the electroscope.

20. Step 3:
When you remove the
ground and the charged
object, the electroscope is
left with a positive charge
because it has lost some
electrons
Charging Permanently
By Induction
Charging Permanently
By Induction

21. Charging By InductionCharging By Induction
Step 1:
When a positively
charged object comes
near a neutral
electroscope, it attracts
the electrons in the
neutral electroscope

22. Charging Permanently
By Induction
Charging Permanently
By Induction
Step 2:
When you ground the
neutral electroscope,
you provide a path for
electrons to go toward
the positive influence.

23. Step 3:
When you remove the
ground and the charged
object, the electroscope is
left with a negative charge
because it has gained some
electrons
Charging Permanently
By Induction
Charging Permanently
By Induction

24. • Once an object is charged, the
charges are trapped on it until they
are given a path to escape
• When electric charges are
transferred very quickly, the process
is called an electrical discharge
Electrical DischargeElectrical Discharge

25. Sparks are an example of
electric discharge

26. Lightning is an example of a very large
electrical discharge caused by induction
Electrical DischargeElectrical Discharge

27. LightningLightning

28. LightningLightning
• Lightning can strike up to 15km from
where it is raining
• If you can hear thunder, you are in
striking distance
• Safe shelter includes large buildings
or vehicles (provided the windows are
rolled up and you do not touch metal
parts of the vehicle)

29. LightningLightning
• Avoid the highest point of land (e.g.
under a tree) because lightning tends
to strike these areas
• Stay away from objects that conduct
electricity (e.g. bicycles, golf clubs,
lawn mowers etc.)