Tricky questions

19th April 1996 at 01:00

Some of my class (Year 5) were putting together simple circuits as part of a science and technology project. At one stage they had to insert a capacitor into the circuit. I know that if you insert a capacitor there is a delay when you switch on before the bulb lights up. But when Simon, aged 10, asked me what was happening, I didn't know how to explain it to him. Any ideas?

One idea is to use the analogy of a bucket. It is like a bucket filling up with water. A little bucket fills up quickly before it overflows, a big bucket takes longer. A little capacitor fills up quickly with electricity, a big one takes longer. That is why a little capacitor causes a short delay and a big one a longer delay before the bulb lights up.

If your pupils have asked a tricky question, please send it to Diane Hofkins at The TES

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