Practical Assessment Task (PAT)


In Units 1 and 4, you were introduced to resistors (like lamps, buzzers and motors), and series and parallel arrangements in circuits.


Electrical safety systems: Panic buttons


Figure 1 Many alarm systems have panic buttons that you can press in an emergency.


Many South Africans are concerned about crime. If someone breaks into your house, you want to be able to call for help. Alarm systems are often built with panic buttons. When a panic button is pushed, the alarm goes off. In some cases, security guards are called automatically. Some systems also turn on flashing lights to attract attention. You are asked to design a panic button system. Make sure the cells, and lamp or buzzer you are using to show that your panic button has been pressed, can be removed and put back easily. You must make your own switches from freely available scrap materials.


Investigation skills


Activity 1 Investigating potential difference, current and resistance


Work in a group of four. Your teacher will supply cells, a lamp, conductors and steel wool and demonstrate each circuit. 1 Look at the circuits at the top of page 151 and note carefully how the components are arranged.


2 Build each circuit. Record how the brightness of the light differs in each circuit.


3 Draw a circuit diagram for each circuit built. 4 Write a short statement about the relationship between potential difference, current and resistance.


150 Practical Assessment Task


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38