A glass prism splits white light into different colours. This phenomenon is called dispersion of light by prism. Which one of the following statements is correct?
- A.Red light will deviate the most and it is because of the reflection of light.
- B.Violet light will deviate the most and it is because of the refraction of light.
- C.Red light will deviate the most and it is because of the refraction of light.
- D.Violet light will deviate the most and it is because of the reflection of light.
Correct answer
Explanation
The correct answer is B. In glass, violet light has the shortest wavelength and the highest refractive index, so it bends the most; dispersion is a result of refraction.
When white light enters a prism, each colour slows down by a different amount, so each is refracted through a different angle and the colours spread out into a spectrum, VIBGYOR. Red, with the longest wavelength, travels fastest in glass and bends the least, while violet bends the most. Isaac Newton showed that a second, inverted prism can recombine the colours into white light. A rainbow forms the same way through raindrops, with refraction, dispersion and internal reflection.
A is wrong because red deviates the least, and dispersion is caused by refraction, not reflection.
C is wrong because, although refraction is the cause, red light deviates the least, not the most.
D is wrong because, although violet deviates the most, the cause is refraction, not reflection.
Exam tip: through a prism, violet bends most and red least; the order of colours is VIBGYOR.
Practice Questions
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1. Alfalfa
2. Amaranth
3. Chickpea
4. Clover
5. Purslane (Kulfa)
6. Spinach
Select the correct answer using the code given below:
- A.1, 3 and 4 only
- B.1, 3, 5 and 6 only
- C.2, 4, 5 and 6 only
- D.1, 2, 4, 5 and 6
Show answer
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- D.Alpha, Beta and Gamma radiations
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- A.Kinetochore
- B.Chromonema
- C.Telomere
- D.Centriole
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