Static Electricity
Science Notes
JC-Learn
JC-Learn
Science Notes
Static Electricity
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Static Electricity
Science Notes
JC-Learn
Static Electricity
Static electricity involves electric charges that collect in one place
and remain stationary.
To understand electricity, you must first know something about the
atom. The atoms of all substances have smaller particles inside them.
 The centre/nucleus of an atom contains neutrons, with a
neutral charge.
 It also contains protons. These protons have a positive
electrical charge.
 In orbit around the nucleus are electrons. These are tiny
particles with a negative charge.
Atoms are generally neutral. This means they have the same number
of protons as electrons. Substances that lose electrons become
positively charged. Other substances that gain electrons will become
negatively charged.
Polythene is a grey/white plastic. When it is rubbed with woolen
cloth, a transfer of electrons occurs. The rod gains electrons; thus, it
is negatively charged. A Perspex rod tends to lose electrons when it is
rubbed on woolen cloth, so it becomes positively charged.
Experiment (not mandatory)
*To demonstrate the force between charged objects
Apparatus required: two polythene rods, two Perspex rods, woolen
cloth, wooden retort stand, paper stirrup, dry thread
Method
1. Charge first rod by rubbing it with woolen cloth. Then suspend
it in paper stirrup.
2. Charge second rod by rubbing it with woolen cloth. Bring it
towards the suspended rod. Note what happens.
3. Repeat experiment for different combinations of rods.
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Static Electricity
Result
Rod 1
Polythene (negative)
Polythene (negative)
Perspex (positive)
Perspex (positive)
Science Notes
Rod 2
Polythene (negative)
Perspex (positive)
Perspex (positive)
Polythene (negative)
JC-Learn
Result
Repulsion
Attraction
Repulsion
Attraction
Like charges repel each other; unlike charges attract.
Effects of static electricity
Useful effects:
 Removes soot from chimneys
 Used in spray painting
Nuisance effects:
 May pick up small electric shock when you touch car door after
journey
 Television screens attract dust
Dangerous effects:
 Lightning can be dangerous result of static electricity.
 A spark of static electricity can be dangerous when coming into
contact with inflammable liquids.
Earthing
Insulators are substances, which do not allow charge to flow through
them.
Conductors are substances, which allow charge to flow through them
freely.
Earthing means connecting an object to the earth by means of a
conductor, so that the object shares its charge with the earth.
 A plastic rod is a good insulator. It can build up and store large
electric charge. This charge has no route to get away. But, if a
conductor touches the charged plastic rod, things change. The
charge can pass through you to the earth, if you touch it,
because you are a conductor.
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Static Electricity
Science Notes
JC-Learn
Examples of earthing:
1. Static electricity – in large hot shop, person picks up charges as
shoes brush off dry carpet. This charge has no easy way to get
to earth. If person then touches metal handrail, they get a small
shock.
2. Lightning conductor – it consists of sharp metal spike, which is
erected at top of building. A copper strip connects this to a
metal plate buried in the ground. The lightning conductor
provides easy route for built-up charge to get to earth. Thus, it
protects the building from being damaged.
Experiment (not mandatory)
*To demonstrate the effect of earthing
Apparatus required: two polythene rods, woolen cloth, metal rod,
two wooden retort stands, two paper stirrups, dry thread
Method
1. Charge two polythene rods by rubbing them with woolen cloth.
2. Suspend each in paper stirrups from retort stand. Bring two
rods close to each other. Because like charges repel, the two
rods repel each other.
3. Now touch each of the rods in several places with metal rod.
Note what happens when two rods are brought close again.
Result
 Nothing happens when the rods are brought close now. They
neither attract nor repel.
Conclusion
 This shows that the two rods lost their charge. They were
earthed. The charge that was on each rod moved off through
the metal rod and through the person holding it to the earth.
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