3.4 Series and parallel connections  (Page 18/2)

TECHNOLOGY

Grade 8

ELECTRICITY

Module 16

SERIES AND PARALLEL CONNEXIONS

Activity 1

To gain knowledge about series and parallel connections by doing practical tests

[LO 1.3]

In a series connection the components are connected in line, one after the other. In a parallel connection the components are connected next to each other. The way in which the components have been connected has a great influence on the delivery of the circuit. In order to understand the result of this kind of connection proper­ly, it is best to look at a few circuits. Your teacher will supply you with the components you need to build the following circuits, either on self-made boards or on bread-boards.

Assignment 1

Construct the following circuits and describe the result on the output component. You may use either a light bulb or LED as output component. Remember that the long pin of the LED is positive. Your teacher will also give you the proper resistor size to protect the LED. If you have a multimeter, you will be able to take readings of the Volts, Ampères and Ohms.

Cells in series

a) What is the total voltage of the battery?

b) What happens if one cell is removed?

The light bulb / LED shines

brightly

dimly

very dimly

(underline the correct answer)

2. Cells in parallel:

a) What is the total voltage of the battery?

b) What happens if one cell is removed?

The light bulb / LED shines

brightly

dimly

very dimly

(underline the correct answer)

3. Light bulbs / LEDs in series:

a) What happens if one light bulb / LED is removed?

b) What happens if one more light bulb / LED is added using the same kind of connection?

c) What is the total voltage of V1 and V2 together?

4. Light bulbs / LEDs in parallel:

a) What happens if one light bulb / LED is removed?

b) What happens if one more light bulb / LED is added using the same kind of connection?

c) What is the total voltage of V1 and V2 together?

5. Resistors in series:

a) What is the function of the resistors?

b) What is the total resistance in the circuit?

Focus Task 1

To master the skill of soldering

[LO 1.10]

Your teacher will give you more information on soldering and also demonstrate how it is done. Soldering wire is a combination of tin and lead. This means that the smoke that is emitted during he soldering process is bad for your health. Try to inhale as little as possible of this smoke.

Apply all safety measures.

Demonstrate your soldering skills by soldering a simple form from wire. A few examples are given below.

Examples of soldering:

Steps in making a wire figure

1 Bend / bind wire.

2 Solder arms.

3 Add extra shapes.

Situation 1

You have been asked to design a Steady-Hand Game that can be used to improve children’s hand-eye coordination. You may use a 3 volt light bulb or a standard LED or 3 volt buzzer – this will switch on when the probe touches the metal frame.

Components required for a circuit.

1 Metal form – bend wire in form as required. (You may use a soldering rod.)

2 Probe – can also be made of soldering rod.

3 LED – the common 3 volt type (or a 3V light bulb).