Figure 1
In fig 1 there is a switch with its cover removed so that its mode of operation can be examined. On the left the blue arrow points towards the open contacts when the switch is in the “off” position, while on the right the arrow points towards the closed contacts in the “on” position. When switching “on” the touching contacts provide a metallic link between the wires connected to the switch.
While children will generally know what a switch does, they will be less clear on how it works. So this week we examined the inside of a switch (with suitably dire warnings against doing this at home) and then used it in a simple bulb and battery circuit.
Fig 2 shows two switches with wires connected, the first with the cover off and the second with its cover on.
Figs 3 and 4 illustrate a simple circuit using a switch, fig 3 with the switch “off” and fig 4 with it “on”. The battery holder is designed for 4 batteries, but we adapt it for use it with one by connecting the crocodile clip to the spring which contacts the negative terminal of the battery.
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SCIENCE Experiment of the Week |
Electrical Circuits (1) 22 April 2008 |