Single correct option
Among the colours of visible light, the one that travels with the highest speed in glass is
- A. violet
- B. green
- C. red
- D. yellow
Show answer and solution
Answer: (C) red
In a medium the speed is c/n. Red light has the smallest refractive index in glass, so it has the highest speed, and it also bends the least. Violet has the largest index, so it is the slowest and bends the most, which is why the prism spreads white light. In vacuum all colours have the same speed.
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