© boardworks ltd 2003 ks4 electricity – simple circuits

© Boardworks Ltd 2003

KS4 Electricity – Simple Circuits


Circuit symbols

Instead of drawing intricate diagrams of electrical components we use circuit symbols to simplify how circuits are set up.

You will need to learn these, how to draw them, and how to identify them.

Filament lamp


Use a textbook or other resource to fill in the table below:

Component Circuit symbol

Fuse

Switch

Resistor

Motor M


Component Circuit symbol

Cell

Voltmeter

Battery

Ammeter A

V

Use a textbook or other resource to fill in the table below:


Breaks in circuits

Set up the circuit shown….

…does the bulb light?

Why does the bulb not light?

There is a break in the circuit.

For electricity to flow in a circuit it must be able to flow from one terminal of the cell or battery to the other terminal.

NO


Letting electricity pass

Do all materials let electricity pass?

Which materials will and which materials will not?

Set up the circuit shown and place different materials in the gap in the circuit. Record which materials let electricity through (the bulb lights if electricity flows).

What do we call a material that lets electricity flow through it? CONDUCTOR

What do we call a material that does not let electricity flow through it?

INSULATOR


Which of these bulbs will light? Build the circuits!

A.

B.

C.x

x

Electricity will always take the easiest path.

It is easier to flow through a wire than through the bulb.

So in circuits B and C the electricity does not pass through the bulb.

The cell or battery still loses energy because , electricity is still flowing.

This type of circuit is known as a SHORT CIRCUIT.


Electron flow

Electricity in wires is a flow of electrons along the wire.

What do we call this flow of electrons? Electrical current


When we talk about current flowing we say that current flows out of the positive terminal of the cell and back into the negative terminal.

Current Flow

Conventional CurrentWhat do we call this flow?


However, the electrons flow from the negative side of the battery to the positive side. These are the particles which are actually moving through the conductor.

Electron Flow


When electrons were discovered, physicists worked out what was really happening. Negatively charged electrons are repelled out of the negative terminal of the cell. They then travel round the circuit and are attracted back to the positive terminal.

Conventional current and Electron flow

Conventional current electrons

Conventional current

What charge do electrons have?

Negative

What do two negative charges do if placed near to each other? They will repel each other.

What will a positive and a negative charge do to each other? They will attract each other.


In an electric c____, current is the flow of e_______. The bigger the current, the m___ electrons are flowing around the circuit. The w___ carry the electrons from one terminal

around the circuit to the other t______.

Current

lamps

ircuitlectrons ore

ireserminal


Set up the two circuits shown:

In which circuit are the bulbs the brightest?In circuit A the bulbs are the brightest.What happens if you unscrew one bulb in Circuit A?The other bulb stays lit.What happens if you unscrew a bulb in circuit B?The other bulb goes out.What do we call circuit A?Parallel CircuitWhat do we call circuit B?Series Circuit

BRIGHTER

DIMMER

A.

B.


Measuring current I

Set up the circuit shown below……

…and then record the current using an ammeter in the places shown below.

What do you notice about the readings?The current is the same for each ammeter.In a series circuit the current is the same wherever you measure it.

When measuring current ammeters are always placed in series.

A

AA


Measuring current II

Set up the circuit shown below……

…then record the current at the locations shown.What do you notice about the readings?

For a parallel circuit, the current that leaves the cell or battery is the same as the current that returns to the cell or battery. The current does not get used up by a circuit, just the energy the electrons are carrying.

A1 = A4

The sum of the currents in the branches of a parallel circuit is the equal to the current that leaves the cell or battery.

A1 = A2 + A3 =A4

Ammeter Current

(A)

A1

A2

A3

A4

0.8

0.8

0.40.4

A1

A2

A3

A4


The v_____ is a measure of how big a push the e_______ are given as they leave the cell or b_____. The bigger the voltage, the bigger the p___.

The cell, battery or p____ s_____ produces the voltage.

Voltage

lamps

oltagelectrons

atteryush

ower upply


Measuring voltage I

V2 V3

V1

Set up the apparatus as shown……

…then record the voltages at the locations shown.What do you notice about the readings?

For a series circuit, the sum of the voltages for each component is equal to the voltage across the cell or battery.

V1 = V2 + V3

NB Voltmeters are connected in parallel

Voltmeter Voltage

(V)

V1

V2

V3

1.50.75

0.75


Series circuit


Measuring voltage II

V1

V2

V3

Voltmeter Voltage

(V)

V1

V2

V3

1.5

1.5

1.5

Set up the apparatus as shown….

..measure the voltage at the locations shown.

What do you notice about your readings?

For a parallel circuit, the voltage across the

cell/battery is the same as the voltage across

each branch.

V1 = V2 = V3


Parallel circuits


Name this circuit symbol.

A. Ammeter

B. Switch

C. Bulb

D. Voltmeter

V


What component is used to measure electrical current?

A. Switch

B. Resistor

C. Ammeter

D. Voltmeter


Which component changes electrical energy into light energy?

A. Bulb

B. Switch

C. Cell

D. Battery


Which component is a store of chemical energy?

A. Bulb

B. Battery

C. Switch

D. Resistor


Which of these materials is not a conductor of electricity?

A. Water

B. Graphite

C. Lead

D. Wood

© boardworks ltd 2003 ks4 electricity – simple circuits

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