WBCHSE Class 12 Physics Dispersion Of Light Very Short Question And Answers

Unit 6 Optics Chapter 4 Dispersion Of Light Very Short Question And Answers

Question 1. Does dispersion of light take place in a vacuum?
Answer: No

Question 2. If white light is allowed to pass through a prism filled with water, will a spectrum be produced?
Answer:  No

Question 3. If rays of light pass through a glass slab which colour of light will have greater velocity—red or blue?
Answer: Red

Question 4. For which colours of light, the refractive index ofthe mate¬
rial of the prism is maximum and minimum?
Answer:

Maximum for violet light and minimum for Red light

Question 5. What colour of light will bend maximum and what colour will bend minimum while passing through a prism?
Answer:

Violet will bend maximum and red will bend minimum

Question 6. Arrange in descending order μb v r, Here μb, μr and μv are the refractive indices of a medium for blue, red and violet colours respectively.
Answer:
μb vr

Question 7. Which one is fundamental—frequency or wavelength, in the analysis of the spectrum?
Answer:
Frequency

Question 8. Does a prism produce colour?
Answer:
No

Question 9. Will a spectrum be produced if the light of a particular colour is allowed to pass through a prism?
Answer:
No

Question 10. Which range of the visible spectrum is most sensitive for our eyes
Answer: Yellow

Question 11. What colour of light Is used while driving a car through fog?
Answer: Yellow

Question 12. Out of red and blue lights for which colour Is the refractive Index of glass greater?
Answer:
br]

Question 13.

1. Which has a larger wavelength, blue or red colour
Answer:
Red colour has a larger wavelength as compared to blue

2. Between red and violet light whose refractivity Is higher?
Answer:
Violet

3. n case of dispersion of light, the angle of deviation for red colour is maximum and it is minimum for violet colour. Is the statement true ot false?
Answer: False

Question 14. What is the range of wavelength of visible light? Can the dispersive power of any medium be negative?
Answer: No

Question 15. On what factors does the dispersion power of the medium depend?
Answer: Nature of the medium and colour of light

Question 16. For which two colours of light is angular dispersion the
Answer:  Violet and Red

Question 17. What is the unit of angular dispersion?
Answer: Degree or radio

Question 18. Does the dispersive power of a prism depend on the angle of the prism?
Answer:
No

Question 19. Which one has the greater dispersive power: crown glass or flint glass?
Answer: Flint glass

Question 20.

1. What are the factors on which angular dispersion of a not? prism depends
Answer:
Angle of prism and nature of the material of the prism

2. Is it true that for a thin prism the angular dispersion of of scattered light? violet and red light rays is equal to the product of the dispersive power of the prism and the deviation of the yellow light ray?
Answer: Yes

Question 21. What are the reasons the formation of a rainbow?
Answer: Dispersion, refraction and reflection of light

Question 22. What is the most essential condition to observe a rainbow?
Answer:

The sun must be situated behind the observer after rainfall or, the observer must stand with his back towards the sun

Question 23.  Under what condition should an object be able to produce a band spectrum?
Answer:
Radioactive condition

Question 24. Under what condition should an object be able to produce a band spectrum?
Answer: Molecular state

Question 25. What will be the nature of the spectrum produced by a light bulb?
Answer:
Line absorption spectrum

Question 26. What kind or type of spectrum solar spectrum is?
Answer: Line absorption spectrum

Question 27. What is the name of the black lines present in the solar spectrum? Answer: Fraunhofer lines

Question 28. What Is the ratio of velocity of ultraviolet rays and infrared rays in a vacuum?
Answer: 1:1

Question 29.

1. How will a blue object look in sodium vapour flame? What kind of spectrum is solar spectrum?
Answer:  Black, line absorption spectrum

2. Write down the nature of spectra produced from an atom, molecule and an incandescent body respectively.
Answer:  Line spectrum, band spectrum, continuous spectrum

3. What is the nature of the spectrum that a red hot heater produces?
Answer: Continuous

4. For the identification of a gas which spectrum is used?
Answer: Line spectrum

5. What characteristics of a body is indicated by the band spectrum?
Answer:
  Atomic characteristics

6. A bunch of red roses kept in a room illuminated with yellow light looks black.—Is the statement correct or not
Answer:
Correct

Question 30. What is the relation between the intensity and wavelength of scattered light
Answer: \(\left[I \propto \frac{1}{\lambda^4}\right]\)

Question 31. ‘In addition to the liquid, solid and gaseous media also exhibit Raman effect’—true or false.
Answer: 
True

Question 32. In the Raman spectrum, what are the names of the spectral lines of longer and shorter wavelengths, apart from the low light ray?
Answer:  Stokes line and anti-stokes line

Question 33. Why is red light used as a danger signal?
Answer:

Because its wavelength is maximum and scattering is minimum]

Question 34. The intensity of Stokes’ lines is more than that of Anti-stokes’ line Is the statement true or false?
Answer:
True

Question 35. Why can’t we see clearly through the fog? Name the phenomenon responsible for it.
Answer:

  1. During fog, the light coming from an object is partly
    deflected by the particles of the fog and does not reach the
    eye of the observer.
  2. For that reason, we cannot see the objects clearly through fog. This responsible phenomenon is called the scattering of light.

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