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Question 1
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(a) What is colour?
(b) Explain briefly the reason why a surface will appear blue.
(c) Outline the contribution of Isaac Newton on colour |
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A good number of candidates were attracted to this question. While most of them responded satisfactorily, a few among them deviated from the requirements of the question by stating the uses and effects of colours. This caused such candidates to lose obtainable marks. Candidates were expected to respond to the question thus:
(a) Colour
- It is a visual response to the wavelength of sunlight identified as red, blue, green, yellow, etc., having the properties of hue, intensityand value.
- It is a sensation caused by light as it is registered on the retina of the eye by the decomposition of light.
- The hues and tints that a pigment gives in the presence of light.
(b) The reason why a surface will appear blue
- A surface will appear blue when it has the characteristic of absorbing all other wavelengths except the blue rays which are reflected to the eyes.
(c) The contribution of Isaac Newton on colour
Sir Isaac Newton discovered the colour band of light called the spectrum or colours of rainbow in 1660.
His experiment was done with a triangular glass prism.
He allowed a beam of white light to fall on the glass and the beam of light was found to have been altered, resulting in a band of seven rainbow colours on a white surface at the other end.
these colours are red, orange, yellow, blue, indigo and violet (ROYGBIV). |
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