force, energy & communication lesson 3 - 4. lesson objectives to be able to explain what happens...

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. The Van de Graaff generator is a machine for charging things up.

2. When switched on, charge builds up on its dome.3. This happens because the charge is deposited on

the bottom of the belt.4. The charge is carried up to the dome by the belt.5. Any insulated object connected to the dome is

charged too.6. 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 = Current X Time

(coulombs) (amperes) (seconds)

Q = I t

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 = Current X Voltage

(watts) (amps) (volts)

P = I V

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!

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 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

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

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

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

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

Hairdryer 2 240

Lightbulb 0.25 60

Kettle 10 240

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

Hairdryer 2 240 480

Lightbulb 0.25 60

Kettle 10 240

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

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 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

Hairdryer 2 240 480

Lightbulb 0.25 240 60

Kettle 10 240 2400