Introducing Electricity – Part

2

Spot the differences

Series Circuit• A series circuit is

one that connects an electrical source with its components one after another, forming one single loop.

Series Circuit

• There is only one path for the current to flow through.

• The current flows through the first bulb, then through the next bulb, to light up all the bulbs.

Disadvantage of a series circuit

• If one of the bulbs is taken out or damaged, the other bulb will not light up.

• Why?- Open circuit- Electricity cannot pass

through the circuit.

Parallel circuit

• A parallel circuit is one that splits into two or more branches.

• There is more than one path for the current to flow through.

• Some current passes through one bulb and the rest flows through the other bulb.

Advantage of Parallel circuits• If one of the bulbs is

taken out or damaged, the other bulb will still light up.

• Why?

- One part of the circuit is still closed.

Series circuit Parallel circuit

Each single component is joined one after the other to form a single path

Divides into two or more branches and has electrical components in each branch

Current flowing through each of the components is the same

Current flowing through the components in the different branches may not be the same

Arrangement of circuitsArrangement of circuits

Lightings at home

• What kind of circuit is more commonly used?

Series circuit – Raise left hand

Parallel circuit – Raise right hand

Why use parallel circuit in the household lightings?

• If one bulb is damaged or switched off, the other bulb can still work.

How about your classroom lightings?

Parallel circuits

Visit the website for a stimulation of series and parallel circuits

• www.electricityineducation.co.uk/keystage3/in/page4.html

Conductor Insulator

A material that allows electricity to pass through it

A material that does not allow electricity to pass through it

Metals Non-metals

Examples: copper, iron, aluminium Examples: plastic, rubber, glass, wood

Note: Our body is a conductor. Hence, we must never touch electricity as it will flow through our body and may kill us.

Conductors and insulatorsConductors and insulators

• Different metals have different conductivity.• In order of decreasing conductivity:

Silver > Copper > Gold > Aluminium

> Chromium > Tungsten > Platinum > Lead[source:

http://www.myhrsb.ca/Functions/Curriculum/eng/science/9/SupplementaryPages/MetalsElectConductivity.htm]

Conductors and insulatorsConductors and insulators

Given a choice, which of the above metals would you use to make connecting wires in a circuit?

Analysing

Classify the following materials into electrical conductors and insulators: iron nail, glass rod, rubber band, wooden stick, aluminium foil, chalk, plastic ruler, copper wire, liquid mercury

Conductors: iron nail, aluminium foil, copper wire, liquid mercury.

Insulators: glass rod, rubber band, wooden stick, chalk, plastic ruler.

Visit the following website to revise what you have learnt:

http://www.hyperstaffs.info/science/work/physics/child/main.html

Click on:

(a)Electricity in the Home

(b)Introduction to Circuits

(c)Circuit Components

(d)Circuit Diagrams

What have you learnt

• Series Circuit

• Parallel Circuit

Homework

• Complete Theory WB Pg. 29 - 33