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.

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 Iron Car headlamp1248 Hi-fi Hairdryer2240 Lightbulb Kettle10240

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 Iron Car headlamp1248 Hi-fi Hairdryer2240 Lightbulb Kettle10240

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 Iron Car headlamp1248 Hi-fi Hairdryer2240 Lightbulb Kettle10240

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 Iron Car headlamp41248 Hi-fi Hairdryer2240 Lightbulb Kettle10240

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 Iron Car headlamp41248 Hi-fi Hairdryer2240 Lightbulb Kettle10240

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 Iron Car headlamp41248 Hi-fi Hairdryer Lightbulb Kettle10240

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 Iron Car headlamp41248 Hi-fi Hairdryer Lightbulb Kettle10240

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 Iron Car headlamp41248 Hi-fi Hairdryer Lightbulb Kettle