The Electromagnetic Spectrum
Light, Sound and Waves


Teaching Guidance for 11-14 Supporting Physics Teaching

Cats and blackout

Angela, a year 7 pupil, came out of the darkroom and was asked whether she was able to see her hand in front of her nose. No, replied Angela, but I bet our cat could have done!

A true story, and worth raising as a further discussion point. Can cats see in the dark? Why do you think that Angela believes her cat can see in the dark? What is it about cats' eyes?

Warning: One year after a blackout activity two boys asked whether they could try to make the science lab a light-tight enclosure. For two weeks they came up at lunch-times and worked with rolls of black paper, blanking off the gaps around windows and doors. Eventually they gave up, admitting that it was impossible to stop all of the light. The technician breathed a sigh of relief!

Teacher Tip: A good room black-out is essential for this and all of the other activities relating to light. On first consideration this particular demonstration may seem to be lacking in potential impact. Experience, however, has shown that the combination of full black-out and a powerful point source of light leads to a quite striking demonstration.

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