| Interactive
Primary Newsletter 27 "If you can't stand the heat..." |
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Black or white? We speak of warm and cool colours, children could be asked which colours they consider warm and which cool. Which is a warm colour black or white? Paint one of the drinks cans black and one white and fill with water. Note the temperature of the water in each can then leave on a sunny window sill for 15 minutes. Can the children guess in which one the water will become warmer? Black surfaces absorb heat more readily than white. In many Mediterranean countries solar heating is used for their hot water supplies. In Greece solar heating cylinders are as common place as TV aerials. Should we have a sunny day this summer it is surprisingly easy to heat water by solar radiation. A black bin liner filled with about a gallon of water left in the sun will heat to around 40oC. |
