EDEXCEL IGCSE / CERTIFICATE IN PHYSICS 2-2
Electric Charge
Edexcel IGCSE Physics pages 66 to 73
Content applying to Triple Science only is shown in
red type on the next slide and is indicated on
subsequent slides by ‘TRIPLE ONLY’
June 17th 2012
Edexcel Specification
Section 2: Electricity
d) Electric charge
identify common materials which are electrical conductors or insulators, including metals
and plastics
describe experiments to investigate how insulating materials can be charged by friction
explain that positive and negative electrostatic charges are
produced on materials by the loss and gain of electrons
understand that there are forces of attraction between unlike charges and forces of
repulsion between like charges
explain electrostatic phenomena in terms of the movement of
electrons
explain the potential dangers of electrostatic charges, eg when fuelling aircraft and
tankers
explain some uses of electrostatic charges, eg in photocopiers and inkjet printers.
Red type: Triple Science Only
Electrical conductors and insulators
An electrical conductor
is a material through
which electric current
flows easily.
All metals are
conductors.
Electrical insulators
have a very high
resistance to the flow of
electric current.
Complete the table below:
copper
rubber
steel
mercury
paper
plastic
diamond
graphite
conductor
1
insulator
2
conductor
3
conductor
insulator
4
insulator
5
insulator
6
conductor
TRIPLE ONLY
Electric charge
Electric charge can be either
positive or negative.
In an atom an electron has a
negative charge that is of the
same size as the positive
charge of a proton.
Neutrons have no electric
charge.
As an atom has the same
number of electrons as protons
it is uncharged.
TRIPLE ONLY
Static and current electricity
Static electricity describes the situation
when electric charges remain stationary.
This occurs best with insulators.
An electric current occurs when electric
charges are moving from one place to
another.
This occurs best with conductors.
TRIPLE ONLY
Charging materials using friction
When certain insulating materials are rubbed against each
other they become electrically charged.
Electrons are rubbed off one material onto the other.
The material that gains electrons becomes negatively
charged.
The material that loses electrons is left with an equal
positive charge.
TRIPLE ONLY
Force and charge
When a charged object is brought close to an
uncharged one the two objects attract each other.
The charged comb
attracts the column of
water
Charged balloon
attracted to a wall
TRIPLE ONLY
Attraction and repulsion
Two bodies that carry different
types of charge attract.
Two bodies that carry the same
type of charge repel.
The law of charges:
LIKE CHARGES REPEL,
UNLIKE ATTRACT.
This boy’s hair has all the
same type of charge!
TRIPLE ONLY
TRIPLE ONLY
Choose appropriate words to fill in the gaps below:
charge remains
Static electricity occurs when electric ________
stationary
____________
on an object.
insulating
rubbing
An __________
object can be charged by __________
it with
electrons and becomes
another insulator. One of them gains ________
positively
negatively charged. The other becomes equally __________
charged.
repel
The law of charges states that; ‘like charges _______,
unlike
attract
_________’.
WORD SELECTION:
attract
insulating electrons
rubbing
positively
repel
charge
stationary
TRIPLE ONLY
Hazards of static electricity
The main danger of static
electricity is in situations
where a spark can cause a
fire or an explosion.
The Buncefield oil depot
explosion (opposite) in
December 2005 was
thought to have been
caused by a spark.
TRIPLE ONLY
Fuel pipe problems
When oil or petrol is
pumped along pipes a
static charge can build
up on the pipe which
could result in a spark.
This could cause an
explosion when the fuel
vapour reacts with
oxygen in the air.
fuel pipe connected to earth
TRIPLE ONLY
Antistatic floors
In operating theatres it is
important that the doctors to
do not become statically
charged when walking
around.
This is because some of the
anaesthetic gases used are
explosive.
Antistatic material is used
for the floor surface so that
any charge is conducted to
earth.
TRIPLE ONLY
Uses of static electricity:
1. Paint spraying
The spray nozzle is connected is
connected to the positive terminal of
an electrostatic generator.
As the paint droplets leave they
repel each other and spread out to
form a fine cloud of paint.
The metal panel to be painted is
connected to the negative terminal.
The negatively charged metal panel
attracts the positively charged paint.
TRIPLE ONLY
2. Ink-jet Printer
Spots of ink are given an electric
charge as they leave the ink nozzle.
The deflecting plates cause the
drops to hit the right part of the
paper.
The charges on the deflecting
plates change many times per
second so that each drop hits the
paper in a different position.
TRIPLE ONLY
3. Photocopier
TRIPLE ONLY
TRIPLE ONLY
4. Smoke precipitator
An electrostatic precipitator is used
to prevent the dust and ash
produced by coal fired power
stations from entering the
atmosphere.
The ash and dust becomes charged
as it passes through the charged
grid of wires.
The ash and dust is then attracted to
the oppositely charged metal plates.
When the plates are shaken the
accumulated ash and dust falls
down to be collected and removed.
Online Simulations
Balloons & Static Electricity - PhET Why does a balloon stick to your
sweater? Rub a balloon on a sweater,
then let go of the balloon and it flies
over and sticks to the sweater. View
the charges in the sweater, balloons,
and the wall.
Electric & Magnetic Forces - 'Whys
Guy' Video Clip (3:30mins) - Shows
Charged Balloon & Effect of a magnet
on a TV screen.
John Travoltage - PhET - Make
sparks fly with John Travoltage.
Wiggle Johnnie's foot and he picks up
charges from the carpet. Bring his
hand close to the door knob and get
rid of the excess charge.
Fuel Ignition While Refuelling A Car Word document with embedded video
clip
Charged Rod & Pith Ball - Iona
Electric Force Tutorial - Science Trek
How photocopying works - University
of Delaware
BBC KS3 Bitesize Revision:
Electrical Charge
BBC AQA GCSE Bitesize Revision:
Attraction & Repulsion
Uses of static electricity
Charge, current, energy and time
relationships
TRIPLE ONLY
Electric Charge
Notes questions from pages 66 to 73
1.
2.
3.
4.
5.
6.
Explain how a material can become charged using friction
(see pages 66 & 67).
Describe a simple experiment to show that like charges repel
and unlike charges attract (see page 67).
Explain with the aid of diagrams how the following devices
make use of static electricity: (a) paint sprayers; (b) ink-jet
printers; (c) photocopiers (see pages 70 & 71).
Describe some of the problems caused by static electricity
(see page 72).
Answer the questions on page 73.
Verify that you can do all of the items listed in the end of
chapter checklist on page 73.
Online Simulations
Balloons & Static Electricity - PhET - Why does a balloon stick to your sweater? Rub a
balloon on a sweater, then let go of the balloon and it flies over and sticks to the
sweater. View the charges in the sweater, balloons, and the wall.
Electric & Magnetic Forces - 'Whys Guy' Video Clip (3:30mins) - Shows Charged
Balloon & Effect of a magnet on a TV screen.
John Travoltage - PhET - Make sparks fly with John Travoltage. Wiggle Johnnie's foot
and he picks up charges from the carpet. Bring his hand close to the door knob and get
rid of the excess charge.
Fuel Ignition While Refuelling A Car - Word document with embedded video clip
Charged Rod & Pith Ball - Iona
Electric Force Tutorial - Science Trek
How photocopying works - University of Delaware
BBC KS3 Bitesize Revision:
Electrical Charge
BBC AQA GCSE Bitesize Revision:
Attraction & Repulsion
Uses of static electricity
Charge, current, energy and time relationships