Advertisements
Advertisements
Question
Define refraction and state the laws of refraction.
Advertisements
Solution
The phenomenon of change in the direction of propagation of light when it passes obliquely from one transparent medium to another is called refraction of light.
Laws of refraction:-
- The incident ray and the refracted ray are on the opposite sides of the normal at the point of incidence, and all three lie in the same plane.
- For a given pair of media, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant.
`sin i/sin r=mu`
This constant is called the refractive index of the second medium with respect to the first medium.
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
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
Name one factor that affects the lateral displacement of light as it passes through a rectangular glass slab.
The speed of light in glass is 2 × 105 km/s. What is the refractive index of glass?
Draw the diagram given below and clearly show the path taken by the emergent ray.
Name a prism required for obtaining a spectrum of Ultraviolet light.
Observe the following figure and answer the questions given under it:
1) How many times does refraction take place in the above figure?
2) What happens to the ray of light when it passes from air to glass?
3) What happens to the ray of light when it passes from glass to air?
4) What are the rays AB and CD in the figure called?
5) Define refraction.
How can you bend light away from the normal?
Draw diagrams to show the refraction of light from glass to air. In diagram, label the incident ray, refracted ray, the angle of incidence (i) and the angle of refraction (r).
A light ray in passing from water to a medium
(a) speeds up
(b) slows down. In each case, give one example of the medium.
What do you understand by the statement the refractive index of glass is 1.5 for white light?
Name the colour of white light which is deviated the most on passing through a prism.
An object is viewed through a glass prism with its vertex pointing upwards. It appears to be displaced upward. Explain the reason.
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 postage stamp kept below a rectangular glass block of refractive index 1.5 when viewed from vertically above it, appears to be raised by 7.0 mm. Calculate the thickness of the glass slab.
Select from the following the best experimental set-up for tracing the path of a ray of light through a glass slab:
(A) I
(B) II
(C) III
(D) IV
After tracing the path of rays of light through a glass slab for three different angles of incidence, a student measured the corresponding values angle of refraction r and angle of emergence e and recorded them in the table given below:
|
S. No. |
∠i |
∠i |
∠e |
|
I |
30° |
20° |
31° |
|
II |
40° |
25° |
40° |
|
III |
50° |
31° |
49° |
The correct observations are:
(A) I and II
(B) II and III
(C) I and III
(D) I, II and III
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
Observe the figure and write accurate conclusion regarding refraction of light.
Fill in the blank to complete the following sentence:
When light travels from a rarer to a denser medium, it bends ...........
Draw an í- `delta` graph for a mono chromatic raY through a glass prism of a plane and mark
(i) `delta` m, the angle of mínimum devíation
(íí) Any two values of i for which value of `delta` ís same.
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?
Rewrite the following statement by selecting the correct option:
If a ray of light strikes a glass slab at an angle of 600 with the surface of the slab, the angle of incidence must be __________________.
What is meant by the refraction of light?
Name the phenomenon responsible in the following case:
Twinkling of stars
Why upper surface of water contained in a beaker and above eye level appears silvery?
Name one main factor on which the direction of bending of a ray of light depends.
A fish swimming in a pond seems nearer than it really is. Explain.
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 relation between the refractive index μ and the velocity of light (vm) in that medium.
Name two instruments of the total refracting prism in which is used.
How does the angle of deviation produced by a prism depend on the colour of light used? Which colour of white light is deviated (i) most, (ii) least, by a prism?
Draw ray of light bending towards the normal while passing from glass to water. Label your diagrams.
The refractive index of glass with respect to air is 1.5. What is the value of the refractive index of air with respect to glass?
Observe the figure and name the ray AB, ray CD, ray GH.
