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Question
You are given a dry cell, a torch bulb with holder, wires and crocodile clips. How would you use them to distinguish between samples of metals and non-metals?
Solution
Take a torch bulb fitted with a holder and connect it to a dry cell using connecting wires, as shown in the figure below. There is a gap between the ends of the crocodile clips A and B; so, no current flows in the incomplete circuit. Hence, the bulb does not light up.
Metals are good conductors of electricity. Hence, if samples of metals are inserted between the clips A and B, the sample will allow an electric current to pass through it and the bulb will light up. But non-metals do not conduct electricity. Hence, the samples of non-metals do not allow any electric current to pass through them and the bulb will not glow.
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