ERIC Number: EJ848932
Record Type: Journal
Publication Date: 2009-May
Abstractor: As Provided
What Colour Is a Shadow?
Hughes, S. W.
Physics Education, v44 n3 p292-295 May 2009
What colour is a shadow? Black, grey, or some other colour? This article describes how to use a digital camera to test the hypothesis that a shadow under a clear blue sky has a blue tint. A white sheet of A4 paper was photographed in full sunlight and in shadow under a clear blue sky. The images were analysed using a shareware program called "ImageJ". The average red, green and blue pixel values in a region of interest drawn on a photograph of the paper in sunlight and shadow were 0.3, 0.32, 0.38 and 0.2, 0.3, 0.5 respectively, demonstrating that a shadow under a blue sky has a blue tint. The experiment would be a useful exercise for a science class. (Contains 3 tables, 2 figures and 3 footnotes.)
Descriptors: Photography, Light, Hypothesis Testing, Science Instruction, Color, Science Experiments, Scientific Principles
Institute of Physics Publishing. The Public Ledger Building Suite 929, 150 South Independence Mall West, Philadelphia, PA 19106. Tel: 215-627-0880; Fax: 215-627-0879; e-mail: firstname.lastname@example.org; Web site: http://journals.iop.org
Publication Type: Journal Articles; Reports - Research
Education Level: N/A
Authoring Institution: N/A