ELECTRICITY

UNIT 4Standard No:23

LESSON 1

WHAT IS ELECTRICITY?

WHAT DO YOU KNOWABOUT ELECTICITY?

Open physics for you pg: 217 - 192

Key wordsElectric circuit

كهربية دائرة

Electric current كهربي تيار

Complete circuitمغلقة دائرة

Incomplete circuit مفتوحة دائرة

Battery بطارية

Bulb مصباح

Switch مفتاح

Wire سلككهربي

Potential difference

الجهد فرق

ACTIVITY 1 :

Each group has :

2 wires Bulb Battery

ACTIVITY 1 :

Procedure :

Use the items you have and make an electric circuit which will turn on the bulb.

Time : 3 min.

electric circuit ( A )

Battery

Bulb

Wire

In this circuit : 1- Did the electricity flow?2- How do you know this?

Complete circuit

2- Where did the electricity come from ?

To answer this question we must go back to the atom structure .

The atom has three particles :

Electron : it has a ……………..charge

proton : it has a ……………....chargeneutron : it is …………….

positive

negative

neutral

Free Electrons Can Move

Free Electrons can Move from Atom to Atom

The free electrons are attracted to atoms where there is an electron missing.It will fill the space just left empty by the first free electron. When this happens all the time, the movement of electrons becomes the "current".

Electricity - electrons moving through a metal wire.

ACTIVITY :

Procedure :

1-Use the items you have and make a complete circuit which has no light bulb

2- keep holding the wires attached to the battery for 2 min.

Does the electricity flow in the wires ?There is no lights on

After 2 minutes What happened to the wire ?

It became warmer

ACTIVITY :

Procedure :

1-Use the items you have and make a complete circuit which has no battery

ACTIVITY :Did the bulb turn on ?Why ?Did the electricity come from wire or battery?

NoBecause there is no battery

Most wires are made of copper which has free electrons

If the electrons are already in the wire, why do we use battery ? Look at this example with water.

Water pump

A

B

C

D E

F

Water pipes

You see a system ofpipes full of water .Would the water move from A to F by itself ?What do we need?

A

V

AB

CD

F

E

Find out the meaning of these symbols :

Compare this with an electrical circuit.Instead of pipes, we have ......Instead of water, we have .......Instead of a pump, we have ......

wireselectrons

a battery

A

V

AB

CD

F

E

switch

Electrode Sourcebattery

wire

voltmeter

Ammeter

What is an electric current?An electric current is a flow of microscopic

particles called electrons flowing through wires

and components .

+ -

In which direction does the current flow ?from the Negative terminal to the Positive terminal

of a cell.

•Look at the two circuits below.

Will the circuit give out light or sound when the switch is closed?

Will the circuit give out light or sound when the switch is closed?

Q:Charge:1 coulomb is the amount of charge that passes

a point when a current of 1 ampere flows for 1 second.

Q = Itelectric current is the rate of flow of chargedParticles (Ampere)

The charge on 1 electron is

1.6×10-19c

q=n×eAmount of charge =number of electron ×charge of one electron

Solve problem:A Current of 0.50A passes through a lamp for 2.0 minutes

a) How much charge passes through the lamp? ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

b) How many electrons pass through the lamp?---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

What are conductors and insulators?

Warm Up

1 .In the diagram above, the water in the pan is changing from a liquid to a gas, or.____

a. Melting c. condensingb. freezingd. evaporating

2 .What is matter?.aThe amount of matter something contains..bEverything in the universe that has mass and

takes up space.cThe amount of salt in water.dThe amount of space that matter takes up.

3 .Study the picture above. When the sun comes out, the snowman melts, or

changes from.____ .asolid to liquid.bliquid to solid.cgas to liquid.dsolid to gas

4 .Buoyancy is__________.eThe ability for an object to float.fTo form a solution with another

material.gThe amount of matter something

contains..hevaporation

What is a conductor?•A conductor is something which allows electricity to

flow through.

•An example of a conductor is:–Scissors–Paper clip–Aluminum foil–Iron–Steel–Copper

What is a Insulator?•An insulator is what makes electricity from not

flowing

•Examples of insulators are:–Cotton–Paper–Plastic–Glass–Rubber

Inquiring Minds Want to Know! Conductor or Insulator? That is the question!

Now take the bag of materials and spread them out in front of

you.Draw the following table

in your journal.As you test each item,

record whether it was a conductor or and

insulator with a

Item Conductor Insulator Did the bulb light?

Spoon

Paper clip

pencil

Rubber band

eraser

Foil

Nail

coin

End of lesson 1