Aim:•Recognise that current will not flow around an incomplete circuit.• Identify a range of materials that allow a current of electricity to flow around a circuit.

Complete and incomplete circuits

1. Build the circuit shown above. What happens to the bulb when the circuitis complete?2. Starting from the positive side of the cell, trace with your finger the pathfollowed by the electricity as it flows around the circuit.3. Now remove one of the wires to the left of the bulb. What happens to thebulb?4. Again, starting from the positive side of the cell, try to trace the path theelectricity should follow around the circuit.5. Reconnect this wire and disconnect a wire which is to the right of the

bulb.What happens?6. Repeat instruction 4.

Questions

1. What is a complete circuit?2. What is an incomplete circuit?3. What happens to the bulb when

the circuit is complete? Explain why this happens.

4. What happens to the bulb when the circuit is incomplete? Explain why this happens.

Conductors and Insulators.

Build the circuit above. Place a variety of materials between the crocodile clips to test them. Record your results in a table.

Conductors and Insulators

Name of Material Conductor or Insulator?

Copy and Complete

Electricity is a flow of _____________ (negatively charged particles).

Electricity can flow through____________ but not through

_____________. ________ are good conductors of electricity.

Electrons

Conductors

Insulators

Metals

Aim:•Show how to represent circuit components as symbols.•Explain the role of cells and switches in circuits.•Describe and understand the effect of adding cells in circuits

Circuit SymbolsVoltmeter

Ammeter

Variable Resistor

Switch

Bulb

Motor

Cell

Battery

Batteries and Switches

Questions:Q1. What happened to the brightness of the bulb when you add more batteries? Explain why

Q2. What happens to the bulb in circuit D? Explain why.

Aim:•Use an ammeter to measure current in a circuit•Describe the effect on current of adding more components in a circuit.•Explain how a fuse works

The flow of currentCurrent in a circuit is ____ used up. Current

which leaves a cell returns to it. Current leaves from the ________ terminal and returns to the negative terminal.

The cell is a device which gives ________to components of the circuit. ___________ is what makes the current flow. A battery with a 9v rating will make the same lamp _________ than one with a 4.5v rating.

notpositive

energy

Voltage

brighter

Which fuse?

Very thin copper wire has a greater resistance than thicker copper wire. The thicker the wire the lower the resistance.

Complete the sentences: breaks melts protectsIf the current flow is too high then the wire in the fuse …… and ……….. The circuit. This ……… the device so that components themselves do not melt.

Fuse

5 amp 13 amp

Wire is… thicker / thinner thicker / thinner

Resistance is… higher / lower higher / lower

Used in… kettle / ipod kettle / ipod

Which fuse?

Very thin copper wire has a greater resistance than thicker copper wire. The thicker the wire the lower the resistance.

If the current flow is too high then the wire in the fuse melts and breaks the circuit. This protects the device so that components themselves do not melt.

Fuse

5 amp 13 amp

Wire is… thinner thicker

Resistance is… higher lower

Used in… ipod kettle

Aim:•Explain the features of series and parallel circuits.•Build a complete parallel and series circuit

Credits!

Series Circuits

Parallel Circuits

Aim:•Use an ammeter to measure current in a parallel circuit•Explain how current behaves in a parallel circuit.

Circuit Blockbusters Credits!

Summary

Measuring current in parallel circuits

Parallel circuits

Current in a parallel circuit is ______ used up. However it may not be the same everywhere you measure it. The current ________ when it comes to a branch. The ______ in the branches _______ up to the current ______ and returning to the ____________.

current

not

splits up

leaving

battery

adds

Aim:•Use analogies to explain how electrical circuits work•Create your own analogy to explain how circuits work.

What is the missing current reading?

A1

A2

A3

A41 2

3

4

A1 = 4 amps

A2 = 3 amps

A3 =

A4 =

Credits!1 amp

4 amps

A circuit is like a central heating system in a house:

Boiler and pump

radiator

High pressurelow pressureThere is a pump that pushes water round the system. The water everywhere starts to move AT THE SAME TIME

There are pipes that CARRY the water.

In the pipes the water is FLOWING.

Flowofwater

An electrical circuit is very similar to a central heating system.The bulb in the circuit is like a radiator. An electrical device uses electrical energy supplied by the circuit.

battery

lampwires

Instead of a flow of water, electricity flows in an electrical circuit. The wires are like pipes; they carry the electricity round the circuit. This is called the electrical current.

The electrical current is pushed by the battery, which has the same function as the pump and boiler.

The strength of push provided by the battery is called its voltage.

A circuit model

Circuit Models

Homework

Research and find out what discoveries the following scientists made about

electricity. Thomas Edison Luigi Galvani Alessandro Volta André-Marie Ampère

Write in your own words what their discovery was and find a picture of the

person to illustrate. (1 page in your book)

Aim:•Describe what produces resistance in a circuit•Explain what effect resistance has on current.

Resistance

Variable Resistors

Aim:•Really just a bit of fun! But try and remember some of the explanations for GCSE to amaze and astound your teachers with your fabulous intelligence!

It’s all about electrons

The Magic Wand

Aim: Revise in preparation for your end of unit test next lesson.