Cambridge IGCSE – Physics notes by Swarnapali Liyanage
STATIC ELECTRICITY
Electricity
Electricity is the flow of electrical charges or power. The charges
could be in the form of electrons or ions.
Static electricity :
Static electricity is the result of an imbalance between negative
and positive charges in an object
Cambridge IGCSE – Physics notes by Swarnapali Liyanage
How insulators are charged by friction :
If, however, and object gains extra electrons, it will gain an
overall negative charge If it loses some of its electrons it will
be left with a positive charge
o Negative charges are the result of gaining
electrons
Positive charges are the result of losing
electrons
Charging by Induction Explained
When a charged object is held close to a conductor,
electrons in the conductor are able to move towards (or
away from) the charged object:
Negative electrons in the aluminium are attracted to the positive
rod
Cambridge IGCSE – Physics notes by Swarnapali Liyanage
In the diagram above, electrons in the aluminium foil are
attracted to the positively charged rod
This causes the top of the foil to become negatively charged,
whilst the bottom edge of it will be left with a positive charge
The attraction between the positive rod and the negative
charges on the top surface of the foil will cause the foil to be
attracted to the rod.
Cambridge IGCSE – Physics notes by Swarnapali Liyanage
Cambridge IGCSE – Physics notes by Swarnapali Liyanage
Demonstrating the static electricity by Gold leaf electroscope\
Cambridge IGCSE – Physics notes by Swarnapali Liyanage
here are various situations where static electricity can pose a
hazard, for example:
The risk of electrocution (from lightning)
The risk of a fire or explosion (due to a spark close to
a flammable gas or liquid).
One common example concerns the refuelling of planes.:
o When a plane is refuelled, the fuel has to be pumped at
a fast rate.
o Friction between the fuel (a liquid insulator) and the
pipe causes the fuel to gain a charge.
o If this charge were to cause a spark the fuel could
ignite.
Diagram showing the use of a bonding line whilst refuelling a place
To prevent this, planes are connected to the earth with a copper wire
(the bonding line) whilst they are being refuelled.
Cambridge IGCSE – Physics notes by Swarnapali Liyanage
This wire removes charge from the plane by carrying it to the earth,
which removes the risk of any sparks.
Difference Between Static & Current Electricity
Static Electricity
The type of electricity that is generated at the surface of material is
known as static electricity.
It produces the motion of negative charges between two bodies.
This electricity can be generated in both conductive and insulator
materials.
In this electricity there is no induction of a magnetic field.
The static electricity is generated for the small-time period.
The instrument that used to measure the static electricity is Gold leaf
electroscope.
The examples of static electricity are lightning strokes, it can also be
generated with the rubbing balloons on hair,
Current Electricity
Current electricity is generated due to the flow of electrons.
The main cause of current electricity is the motion of electrons.
The current electricity is generated only in the conductive substances.
Current electricity produces a magnetic field.
The exiting time period of current electricity is larger than the static
electricity.
Its value can be measured with the use of analog and digital meter.
Cambridge IGCSE – Physics notes by Swarnapali Liyanage
Its common applications are working fan, tube light, machines, motor,
etc.
