Vidaara.orgClass 10 · Physics
CodeVID-P10-02-PRI-01
Prism, Dispersion & Atmospheric Optics — Assignment
Name: ____________________
Roll No.: __________
Date: ____________
General Instructions
- All questions are compulsory.
- Section A carries 1 mark each, Section B 2 marks, Section C 3 marks and Section D 5 marks.
- Draw neat labelled diagrams where asked. Only final answers are given at the end — for full solutions, raise your doubts with your teacher.
Section A — Multiple Choice Questions
5 × 1 = 5 marks
1.
The band of seven colours obtained from white light is called the
- A.rainbow only
- B.spectrum
- C.shadow
- D.image
2.
In VIBGYOR, the letter V stands for
- A.violet
- B.vermilion
- C.vivid
- D.vapour
3.
The Sun appears red at sunset because of
- A.dispersion
- B.scattering of blue light
- C.total internal reflection
- D.diffraction
4.
A rainbow appears in the sky
- A.towards the Sun
- B.opposite the Sun
- C.directly overhead
- D.only at noon
5.
Scattering of light by colloidal particles is the
- A.Doppler effect
- B.Tyndall effect
- C.photoelectric effect
- D.greenhouse effect
Section B — Short Answer (2 marks)
3 × 2 = 6 marks
6.
Define dispersion of light.
7.
Why does a planet not twinkle?
8.
What is the angle of deviation of a prism?
Section C — Short Answer (3 marks)
2 × 3 = 6 marks
9.
Explain how a rainbow is formed.
10.
Why does the sky appear dark to an astronaut in space?
Section D — Long Answer (5 marks)
1 × 5 = 5 marks
11.
With a labelled diagram, explain dispersion of white light by a prism and how it can be recombined into white light.
Answer Key
Section A — Multiple Choice Questions
- (B) spectrum
- (A) violet
- (B) scattering of blue light
- (B) opposite the Sun
- (B) Tyndall effect
Section B — Short Answer (2 marks)
- The splitting of white light into its seven constituent colours on passing through a prism.
- It is close and appears as an extended source, so the brightness variations average out.
- The angle between the direction of the incident ray and the emergent ray.
Section C — Short Answer (3 marks)
- Sunlight is refracted, internally reflected and refracted again by raindrops, dispersing into colours; seen opposite the Sun.
- There is no atmosphere to scatter sunlight, so no scattered light reaches the eyes and the sky looks dark.
Section D — Long Answer (5 marks)
- Prism splits white light into VIBGYOR (violet most, red least deviated); a second inverted prism recombines the colours into white light (Newton).
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