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? - Science and Technology 1


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?


  • 50°

  • 90°

  • 60°

  • 40°




The ray of light strikes at an angle of 50 with the horizontal. The angle of incidence is with respect to the normal, so the angle of incidence is 90° − 50° = 40°.

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2013-2014 (March)


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

Explain how spectrum is formed.

When rays of light are incident on a glass slab then the incident ray and emergent ray are _________ each other.

  1. perpendicular
  2. parallel
  3. opposite
  4. concurrent

What is a spectrum?

Write a short note on dispersion of light.

Define refraction and state the laws of refraction.

Explain how the formation of a rainbow occurs.

A student traces the path of a ray of light passing through a rectangular glass slab and marks the angle of incidence i, angle of refraction r and angle of emergence e, as shown.

The correctly marked angle(s) is/are

(A) ∠ i only

(B) ∠ e only

(C) ∠ r only

(D) ∠ i and ∠ e

Why do we get a spectrum of seven colors when white light is dispersed by a prism?

Explain the term absolute refractive index of a medium and write an expression to relate it with the speed of light in vacuum.

State the dependence of angle of deviation On the refractive index of the material of the prism.

Draw the diagram of refraction of light in the glass slab

Why is the ratio of the velocities of light of wavelengths 4000Å and 8000Å in vacuum 1: 1?

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 does the refractive index of a medium depend on the wavelength of light used? 

How does the angle of minimum deviation produces by a prism change with increase in : 

the refracting angle of prism? 

A ray of light is passing from a transparent medium 1 to another transparent medium 2 (i) Speed up (ii) slows down. In each case, state whether the refractive index of medium 2 is equal to, less than or greater than the refractive index of medium 1. 

Name the colour of white light which is deviated (i) the most, (ii) the least, on passing through a prism. 

A Water pond appears to be 2.7 m deep. If the refractive index of water is 4/3, find the actual depth of the pond. 


The critical angle for glass-air interface is:
(a) 24° (b) 48° (c) 42° (d) 45°

A student has traced the path of a ray of light through a glass slab as follows. If you are asked to label 1, 2, 3 and 4, the correct sequencing of labeling  ∠i, ∠e, ∠r and lateral displacement respectively is

(a) 2, 1, 3, 4

(b) 1, 2, 3, 4

(c) 1, 3, 2, 4

(d) 1, 3, 4, 2

“A ray of light incident on a rectangular glass slab immersed in any medium emerges parallel to itself.” Draw labelled ray diagram to justify the statement. 

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.
















The correct observations are:

(A) I and II

(B) II and III

(C) I and III

(D) I, II and III

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


(D) IV

A ray of light falls normally on the surface of a transparent glass slab. Draw a ray diagram to show its path and also mark angle of incidence and angle of emergence.

While tracing the path of a ray of light passing through a rectangular glass slab a student tabulated his observations as given below:





















The correct observations is:

(A) I

(B) II


(D) IV

While performing the experiment on tracing the path of a ray of light through a rectangular glass slab, in which of the following experimental set-ups is a student likely to get best results? P1 and P2 are the positions of pins fixed by him.

(A) I

(B) II


(D) IV

Four students A, B, C and D traced the paths of incident ray and the emergent ray by fixing pins P and Q for incident ray and pins R and S for emergent ray for a ray of light passing through a glass slab.

The correct emergent ray was traced by the student: 

(1) A

(2) B

(3) C

(4) D

Observe the figure and write accurate conclusion regarding refraction of light.

What is the correct reason for blinking / flickering of stars? Explain it.
a) The blasts in the stars.
b) Absorption of star light by the atmosphere.
c) Motion of the stars.
d) Changing refractive index of gases in the atmosphere.

The diagram below shows a light source P embedded in a rectangular glass block ABCD of critical angle 42°. Complete the path of the ray PQ till it emerges out of the block. [Write necessary angles].

State any two ways of increasing the frequency of vibration of a stretched string.

Light of a single colour is passed through a liquid having a piece of glass suspended in it. On changing the temperature of liquid, at a particular temperature, the glass piece is not seen.

Why is the light of a single colour used ?

Choose the correct alternative and rewrite the following:

A glass slab is placed in the path of convergent light. The point of convergence of 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 __________________.

Glass is transparent in nature. Why does glass powder look opaque? When water is poured over it, it again becomes transparent. Why?

A ray of light is incident at an angle of 45° on one face of a rectangular glass slab of thickness 10 cm and refractive index 3/2. Calculate the lateral shift produced ______.

Draw the ray diagram of a glass slab having medium A and B for the velocity of light ray VA and VB respectively and define Snell's law.

  1. If VB = 1.5 VA, then which medium is denser?
  2. What is the refractive index of A with respect to B?
  3. What is the refractive index of B with respect to A?

Observe the figure and name the ray AB, ray CD, ray GH.


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