Force, Energy

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Force, Energy Communication

• Lesson 3 - 4

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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.

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Van de Graaf
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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

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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.

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Van de Graaff how it works

• 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.

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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. ..

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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!

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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. ..

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Key word glossary

• CHARGE .

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Key word glossary

• CHARGE .a store of electricity, usually caused
  by electrons

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Key word glossary

• CHARGE .a store of electricity, usually caused
  by electrons
• CURRENT

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Key word glossary

• CHARGE .a store of electricity, usually caused
  by electrons
• CURRENT a movement of electrical charge.

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Key word glossary

• CHARGE .a store of electricity, usually caused
  by electrons
• CURRENT a movement of electrical charge
• AMPS

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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

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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.

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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

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Goodie! Time for some equations.
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Goodie! Time for some equations.

• You need to KNOW these equations.

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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.

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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.

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For a steady current in a circuit
Charge passed Current X Time
(coulombs) (amperes)
(seconds) Q I t
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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

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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

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Electric power

• The power within a circuit can be worked out if
  the current and voltage are known, using the
  following equation.

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Electric power

• The power within a circuit can be worked out if
  the current and voltage are known, using the
  following equation.

Electrical power Current X
Voltage (watts) (amps) (volts) P
I V
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Electric power

• The power within a circuit can be worked out if
  the current and voltage are known, using the
  following equation.

Electrical power Current X
Voltage (watts) (amps) (volts) P
I V
The more power something the uses, the more
electricity it uses, the more expensive it is to
run!
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We will be back to those equations later

• . You will need them for your homework!

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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.

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Power who is paying the bill

• Complete this table

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Power who is paying the bill

• Copy and complete this table

Appliance Current, I Voltage, V
Power (amps) (volts)
P I x V (watts) Television 0.83
240 Iron 4.0 240 Car
headlamp 12 48 Hi-fi 0.83 200 Hairdryer 2
240 Lightbulb 0.25 60 Kettle 10 240
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Power who is paying the bill

• Copy and complete this table

Appliance Current, I Voltage, V
Power (amps) (volts)
P I x V (watts) Television 0.83
240 200 Iron 4.0 240 Car
headlamp 12 48 Hi-fi 0.83 200 Hairdryer 2
240 Lightbulb 0.25 60 Kettle 10 240
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Power who is paying the bill

• Copy and complete this table

Appliance Current, I Voltage, V
Power (amps) (volts)
P I x V (watts) Television 0.83
240 200 Iron 4.0 240 960 Car
headlamp 12 48 Hi-fi 0.83 200 Hairdryer 2
240 Lightbulb 0.25 60 Kettle 10 240
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Power who is paying the bill

• Copy and complete this table

Appliance Current, I Voltage, V
Power (amps) (volts)
P I x V (watts) Television 0.83
240 200 Iron 4.0 240 960 Car
headlamp 4 12 48 Hi-fi 0.83 200 Hairdryer
2 240 Lightbulb 0.25 60 Kettle 10 240
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Power who is paying the bill

• Copy and complete this table

Appliance Current, I Voltage, V
Power (amps) (volts)
P I x V (watts) Television 0.83
240 200 Iron 4.0 240 960 Car
headlamp 4 12 48 Hi-fi 0.83 240 200 Hairdry
er 2 240 Lightbulb 0.25 60 Kettle 10 240
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Power who is paying the bill

• Copy and complete this table

Appliance Current, I Voltage, V
Power (amps) (volts)
P I x V (watts) Television 0.83
240 200 Iron 4.0 240 960 Car
headlamp 4 12 48 Hi-fi 0.83 240 200 Hairdry
er 2 240 480 Lightbulb 0.25 60 Kettle 10
240
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Power who is paying the bill

• Copy and complete this table

Appliance Current, I Voltage, V
Power (amps) (volts)
P I x V (watts) Television 0.83
240 200 Iron 4.0 240 960 Car
headlamp 4 12 48 Hi-fi 0.83 240 200 Hairdry
er 2 240 480 Lightbulb 0.25 240 60 Kettle 1
0 240
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Power who is paying the bill

• Copy and complete this table

Appliance Current, I Voltage, V
Power (amps) (volts)
P I x V (watts) Television 0.83
240 200 Iron 4.0 240 960 Car
headlamp 4 12 48 Hi-fi 0.83 240 200 Hairdry
er 2 240 480 Lightbulb 0.25 240 60 Kettle 1
0 240 2400