What is electricity?  (Page 4/2)

Technology

Grade 7

Electricity

Module 10

What is electricity?

Background

Electricity is a type of energy. An object has electrical energy when it has the ability to conduct electricity. Electricity is measured in Volts.

Electrical energy can be easily converted to other forms of electricity.

There are two main types of electricity:

• main stream electricity
• battery electricity

Battery-electricity

Electrical energy are stored in batteries. The energy in batteries are called chemical energy. When electrical energy moves, the electrons flows in an electrical circuit.

The basic elements of an electrical circuit is:

a source of energy e.g. a battery

Sketch	Symbol

a conductor e.g. a sort of metal in the shape of a wire

Sketch	Symbol

a switch to form an open or closed circuit

Sketch	Symbol

a load e.g. a source of light, sound, motion or heat

Sketch	Symbol
a light
a buzzer
an electrical motor

Two or more of the same component in an electric circuit can be connected in two different ways in the circuit;

• in series where a positive pole of one cell is linked to the negative pole of another cell;
• in parallel where all the positive poles of the cells are connected with one another and all the negative poles are also connected like this.

Advantage of cells in series – current supply becomes more powerful

Advantage of cells in parallel – the cells can produce the same current for longer.

To the teacher:

These worksheets should be done in groups. Each group can construct a different circuit and then explain it to the rest of the class before completing a worksheet. A class should be divided into 7 groups, because there are 7 worksheets. This would save a huge amount of time. Each group should construct a test circuit with a switch, 1,5 V lamp, lamp holder and a 1,5 V cell in a cell holder. First screw the holders and switch on the board, add the wire between them and then add the cell and lightbulb.

Equipment and tools needed:

• 1,5 V batteries
• 1.5 V light bulbs
• light bulb holders
• wire/flex
• 7 strip connectors
• battery holders
• 7 switches
• small screws
• flat nose and star screwdrivers
• 7 pieces of insulation board 150 mm by 150 mm
• connectors
• buzzers with a low voltage
• diodes and resistors

Assignment 1:

To investigate by means of a simple practical test[lo 1.3]

To extract relevant data [lo 1.4.4]

To evaluate the system [lo 1.12]

To show knowledge and understanding of electric circuits [lo 2.2]

WORKSHEET 1:

• Connect one 1,5 V cell in a battery holder to a 1,5 V lamp in a lamp holder with wire and a switch on a piece of insulation board.
• Make a simple drawing of the circuit.

1.3 Draw a circuit diagram of the circuit, using the correct symbols.

1.4 Underline:

The light bulb shines (very brightly/bright/dimly/ not at all).

WORKSHEET 2:

2.1 Connect one 1,5 V cell in a cell holder to two 1,5 V lamps in two lamp holders in parallel using wire and adding a switch on a piece of insulation board.

• Draw a circuit diagram of the circuit.
• Unscrew one of the lamps from its holder. What happens to the other lamp? Explain why this happens.
• Underline:

The light bulbs shine (very brightly/ brightly/ dimly/ not at all).