Transcript Force, Energy & Communication

Force, Energy &
Communication
Lesson 3 - 4
Lesson Objectives





To be able to explain what happens with a
Van De Graaff generator.
To describe some practical applications of
static electricity
To be secure in the vocabulary of electricity
To know an be able to use Q = It and P =IV
To appreciate differences in the amount of
electricity used by different appliances.
Van de Graaf
Van de Graaff – how it works




Stick the picture of the Van de Graaff in your
exercise books.
Read the sentences that follow.
Decide on the most logical order to put the
sentences in.
Copy the sentences into your book in the
correct order
Van de Graaff – how it works






This happens because the charge is deposited on
the bottom of the belt.
If too much charge builds up on the dome it
discharges itself by letting sparks fly to any nearby
object.
The Van de Graaff generator is a machine for
charging things up.
When switched on, charge builds up on its dome.
The charge is carried up to the dome by the belt.
Any insulated object connected to the dome is
charged too.
Van de Graaff – how it works
1.
2.
3.
4.
5.
6.
The Van de Graaff generator is a machine for
charging things up.
When switched on, charge builds up on its dome.
This happens because the charge is deposited on
the bottom of the belt.
The charge is carried up to the dome by the belt.
Any insulated object connected to the dome is
charged too.
If too much charge builds up on the dome it
discharges itself by letting sparks fly to any nearby
object.
Uses of static electricity





You will be given this
information sheet.
It has 4 sections.
You are to make notes
on each four sections
by using bullet points.
No more than 4 bullet
points per section.
e.g. …..
Uses of static electricity
Electrostatic precipitator
 Used to remove particles
from power station smoke
 Particles in smoke are given
a positive charge
 They are attracted to large
plates with negative charge.
 Particles then easily
removed from plates.
 Easy!
Uses of static electricity





You will be given this
information sheet.
It has 4 sections.
You are to make notes
on each four sections
by using bullet points.
No more than 4 bullet
points per section.
e.g. …..
Key word glossary

CHARGE ….
Key word glossary

CHARGE ….a store of electricity, usually
caused by electrons
Key word glossary


CHARGE ….a store of electricity, usually
caused by electrons
CURRENT …
Key word glossary


CHARGE ….a store of electricity, usually
caused by electrons
CURRENT … a movement of electrical
charge.
Key word glossary



CHARGE ….a store of electricity, usually
caused by electrons
CURRENT … a movement of electrical
charge
AMPS…
Key word glossary



CHARGE ….a store of electricity, usually
caused by electrons
CURRENT … a movement of electrical
charge
AMPS… a measure of the amount of charge
in a current
Key word glossary




CHARGE ….a store of electricity, usually
caused by electrons
CURRENT … a movement of electrical
charge
AMPS… a measure of the amount of charge
in a current
VOLTAGE….
Key word glossary




CHARGE ….a store of electricity, usually
caused by electrons
CURRENT … a movement of electrical
charge
AMPS… a measure of the amount of charge
in a current
VOLTAGE….the amount of force on a charge
Goodie! Time for some
equations.
Goodie! Time for some
equations.
You need to KNOW these equations.
Charge and current


Electric charge is
measured in
coulombs, C.
One coulomb is defined
as the amount of
charge passing a point
in the circuit each
second, when the
current is one amp.
Charge and current

In other words, a
current of one ampere
is equal to a rate of flow
of charge of one
coulomb per second.
For a steady current in a circuit
Charge passed
(coulombs)
=
Current X
Time
(amperes)
(seconds)
Q = It
Electric power





Important revision!!
Power is a measure of
how much energy there
is per second.
Energy is measured in
joules
Time is measured in
seconds
So power is measured
in joules per second
Electric power



BUT “joules per
second” is a bit of a
mouthful.
So we use another unit.
1 joule per second is
called 1 watt
Electric power

The power within a circuit can be worked out
if the current and voltage are known, using
the following equation.
Electric power

The power within a circuit can be worked out
if the current and voltage are known, using
the following equation.
Electrical power
(watts)
=
Current
(amps)
P = IV
X
Voltage
(volts)
Electric power

The power within a circuit can be worked out
if the current and voltage are known, using
the following equation.
Electrical power
(watts)
=
Current
(amps)
X
Voltage
(volts)
P = IV
The more power something the uses, the more electricity it
uses, the more expensive it is to run!
We will be back to those
equations later
…. You will need them for your
homework!
Power – who is paying the bill

You will be given an envelope with pictures of
a number of appliances in them.

Take out the pictures and arrange them in a
league table, with the appliance which you
think uses the most electricity at the top and
the one that uses the least at the bottom.
Power – who is paying the bill

Complete this table
Power – who is paying the bill

Copy and complete this table
Appliance
Current, I
Voltage, V
(amps)
(volts)
Television
0.83
240
Iron
4.0
Car headlamp
0.83
Hairdryer
2
Lightbulb
0.25
Kettle
10
P = I x V (watts)
240
12
Hi-fi
Power
48
200
240
60
240
Power – who is paying the bill

Copy and complete this table
Appliance
Current, I
Voltage, V
(amps)
(volts)
Television
0.83
240
Iron
4.0
Car headlamp
0.83
Hairdryer
2
Lightbulb
0.25
Kettle
10
P = I x V (watts)
200
240
12
Hi-fi
Power
48
200
240
60
240
Power – who is paying the bill

Copy and complete this table
Appliance
Current, I
Voltage, V
(amps)
(volts)
Television
0.83
240
Iron
4.0
Car headlamp
Hi-fi
0.83
Hairdryer
2
Lightbulb
0.25
Kettle
10
Power
P = I x V (watts)
200
240
960
12
48
200
240
60
240
Power – who is paying the bill

Copy and complete this table
Appliance
Current, I
Voltage, V
(amps)
(volts)
Television
0.83
240
Iron
4.0
Car headlamp 4
Hi-fi
0.83
Hairdryer
2
Lightbulb
0.25
Kettle
10
Power
P = I x V (watts)
200
240
960
12
48
200
240
60
240
Power – who is paying the bill

Copy and complete this table
Appliance
Current, I
Voltage, V
(amps)
(volts)
Television
0.83
240
Iron
4.0
Power
P = I x V (watts)
200
240
960
Car headlamp 4
12
48
Hi-fi
0.83
240
200
Hairdryer
2
240
Lightbulb
0.25
Kettle
10
60
240
Power – who is paying the bill

Copy and complete this table
Appliance
Current, I
Voltage, V
(amps)
(volts)
Television
0.83
240
Iron
4.0
Power
P = I x V (watts)
200
240
960
Car headlamp 4
12
48
Hi-fi
0.83
240
200
Hairdryer
2
240
480
Lightbulb
0.25
Kettle
10
60
240
Power – who is paying the bill

Copy and complete this table
Appliance
Current, I
Voltage, V
(amps)
(volts)
Television
0.83
240
Iron
4.0
Power
P = I x V (watts)
200
240
960
Car headlamp 4
12
48
Hi-fi
0.83
240
200
Hairdryer
2
240
480
Lightbulb
0.25
240
60
Kettle
10
240
Power – who is paying the bill

Copy and complete this table
Appliance
Current, I
Voltage, V
(amps)
(volts)
Television
0.83
240
Iron
4.0
Power
P = I x V (watts)
200
240
960
Car headlamp 4
12
48
Hi-fi
0.83
240
200
Hairdryer
2
240
480
Lightbulb
0.25
240
60
Kettle
10
240
2400