Advertisements
Advertisements
Question
Write a short note on dispersion of light.
Advertisements
Solution
Dispersion of light:-
The phenomenon of splitting of light into its component colours is called dispersion of light. When white light passes through a glass prism, it spreads out into a band of different colours which constitute the spectrum of light. The colours in the spectrum of white light are violet, indigo, blue, green, yellow, orange and red. Dispersion takes place because the refractive index of a material such as glass or water is different for different colours. It is maximum for violet colour and minimum for red colour. Hence, in the spectrum of white light obtained with a prism, violet light is deviated the most, while red light is deviated the least. The deviation of light corresponding to other colours lies in between these two colours.
APPEARS IN
RELATED QUESTIONS
When a ray of light travels from air to glass slab and strikes the surface of separation at 90°, then it …………….
(a) bends towards normal
(b) bends away from normal
(c) passes unbent
(d) passes in zigzag way
Choose the correct alternative and rewrite the following sentence.
A ray of light strikes the glass slab at an angle of 50°. What is the angle of incidence?
After tracing the path of a ray of light passing through a rectangular glass slab for four different values of the angle of incidence, a student reported his observations in tabular form as given below:
| S.No | ∠ i | ∠ r | ∠ e |
| I | 30° | 19° | 29° |
| II | 40° | 28° | 40° |
| III | 50° | 36° | 50° |
| IV | 60° | 40° | 59° |
The best observation is
(A) I
(B) II
(C) III
(D) IV
On the basis of the experiment, "To trace the path of a ray of light through a rectangular glass slab", students of a class arrived at which one of the following conclusions?
(A) Angle of incidence is greater than the angle of emergence.
(B) Angle of emergence is smaller than the angle of refraction.
(C) Emergent ray is parallel to the refracted ray.
(D) Incident ray and emergent ray are parallel to each other.
Write a relationship between the angle of incidence and angle of refractions for a given pair of media
Draw the diagram of refraction of light in the glass slab
When a lighted candle is held in front of a thick plane glass mirror, several images can be seen, but the second image is the brightest, give reason.
When light travels from a rarer to a denser medium, its speed ______.
When a ray of light from air enters a denser medium, it ______.
The highest refractive index is of ______.
In fig 4.18, name the ray which represents the correct path of light while emerging out through a glass block.
Fig 4.31 below shows a light ray of single colour incident normally on two prisms A and B. In each case draw the path of the ray of light as it enters and emerges out of the prism. Mark the angle wherever necessary.
A coin is places at the bottom of a beaker containing water (refractive index = 4/3) to a depth of 12 cm. By what height the coin appears to be raised when seen from vertically above?
Select from the following the best set-up for tracing the path of a ray of light through a rectangular glass slab:
(A) I
(B) II
(C) III
(D) IV
While tracing the path of a ray of light passing through a rectangular glass slab a student tabulated his observations as given below:
|
S.NO. |
∠i |
∠r |
∠e |
|
I |
60° |
40° |
61° |
|
II |
50° |
36° |
51° |
|
III |
40° |
28° |
39° |
|
IV |
30° |
20° |
31° |
The correct observations is:
(A) I
(B) II
(C) III
(D) IV
(i) What is the relation between the refractive index of water with respect to air `("_aμ_\text(w))` and the refractive index of air with respect to water `("_\text(w)μ_ a)` .
(ii) If the refractive index of water with respect to air `("_aμ_\text(w))` is`5/3`. Calculate the refractive index of air with respect to water `("_\text(w)μ_ a)` .
Which of the following has the highest refractive index:
Fill in the blank to complete the following sentence:
When light travels from a rarer to a denser medium, it bends ...........
Which colour of light travels fastest in any medium except air?
Using the curve, how do you infer that for given prism, the angle of minimum deviation δmin is unique for the given light?
Name the phenomenon responsible in the following case:
Apparent bending of a stick in water
Which colour of light travels fastest in any medium except air?
During sunset and sunrise, the sun is seen when it is slightly below the horizon. Give reason.
A glass slab is placed over a page on which the word VIBGYOR is printed with each letter in its corresponding colour.
- Will the image of all the letters be in the same place?
- If not, the state which letter will be raised to the maximum. Give a reason for your answer.
State the factors on which the angle of deviation depends.
State the relation between the refractive index μ and the velocity of light (vm) in that medium.
What should be the ratio of the speed of light through the liquid to the speed through the glass so that there is no refraction of light at the boundaries of the glass block when the system is illuminated by the light of one colour?
Define the term refractive index of a medium in terms of velocity of light.
What do you understand by the deviation produced by a prism?
Complete the ray diagram showing its emergence into the air after passing through the prism.
Two parallel rays of Red and Violet travelling through the air, meet the air-glass boundary as shown in the above figure. Will their paths inside the glass be parallel? Give a reason for your answer.
The diagram shows the path of a ray of light through a rectangular glass block placed in a liquid of uniform density.
(a) Does the light speed up or slow down in the glass,
(b) Give the reason for your answer.
Trace a ray of light incident at 30° on a surface if travelling from glass to air. What is the angle of refraction in this case? (R.I. for glass = 3/2).
Explain with the help of a diagram of how fish is able to see the objects above it.
The velocity of light in diamond is 121000 kms-1. What is its refractive index?
Which colour of white light travels fastest in any medium except air?
What is lateral displacement?
