A soft cell

13th July 2007 at 01:00
Physics

Age 11 to 14

Teaching electricity can sometimes be difficult because pupils can find it hard to visualise what you are talking about. So when I introduce the concept of potential difference, I use a toy garage with a wind-up car lift to represent a cell.

A car then represents one of the charges (current) in the circuit. I place it on the lowest level of the lift and then slowly move it up to higher levels. As this happens, I explain to the pupils how a chemical reaction is taking place in the cell (in this example, in my arm) and raising the charges to a higher potential energy level.

If we raise the car to the first level, it has gained energy but not as much as if we raise it to the second level, etc. I explain that the voltage is the amount of energy needed to raise each car (unit of charge). Once at the top of the lift, the car can run down the ramp, similar to the charges flowing around the circuit.

The only thing to be aware of and explain is that when current flows, it doesn't start in the cell but all of the charges start moving throughout the circuit as soon as it is connected

Andrea Mapplebeck is a professional development leader at the National Science Learning Centre

www.slcs.ac.uknational

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