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Question
The wavelengths for the light of red and blue colours are roughly 7.8 × `10^7` m and 4.8 × `10^7` m respectively.
(a) Which colour has the greater speed in vacuum?
(b) Which colour has the greater speed in glass?
Solution
(a) In vacuum, both have the same speeds.
(b) In a glass, red light has greater speed.
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