MCQs

1. [2081 GIE ‘B’] A ray of light strikes a glass plate at an angle of 60^o. If the reflected and refracted rays are perpendicular to each other. What is the refractive index of glass?
   a. [latex]\frac{1}{\sqrt{3}}[/latex]
   b. [latex]\frac{\sqrt{3}}{2}[/latex]
   c. [latex]\frac{2}{\sqrt{3}}[/latex]
   d. [latex]\sqrt{3}[/latex]
2. [2081 B/C] A polarizer is used to
   a. reduce intensity of light                        
   b. produce diffracted light
   c. increase intensity of light                     
   d. produce unpolarized light
3. [2081 ‘D’] Critical angle for a glass is 42^o. What will be the polarizing angle for it?
   a.   30^o                              
   b. 45^o                          
   c. 56^o                          
   d. 65^o
4. [2080 GIE ‘A’] The critical angle of a certain medium is [latex]sin^{-1}(3/5)[/latex]. Then the polarizing angle of the medium will be
   a. [latex]tan^{-1}(\frac{4}{3})[/latex]
   b. [latex]tan^{-1}(\frac{3}{4})[/latex]
   c. [latex]tan^{-1}(\frac{3}{5})[/latex]
   d. [latex]tan^{-1}(\frac{5}{3})[/latex]
5. [2080 GIE ‘B’] The diagram represents a beam of unpolarized light incident on a diamond of refractive index [latex]\mu[/latex]. At an angle of incidence [latex]\theta_p[/latex], the beam reflected from the diamond is completely plane polarized normal to the plane of page. The relation between [latex]\theta_p[/latex] and [latex]\mu[/latex] is

1. [latex]\mu sin\theta_p = 1[/latex]
2. [latex]\mu cot\theta_p = 1[/latex]             
3. [latex]\mu tan\theta_p = 1[/latex]
4. [latex]\mu cos\theta_p = 1[/latex]

6. [2080 ‘P’] A ray of light strikes a glass plate at an angle of incidence 60^o. If the reflected and refracted rays are perpendicular to each other in interface, what is the refractive index of glass?
   a. [latex]\frac{1}{\sqrt{3}}[/latex]
   b. [latex]\frac{\sqrt{3}}{2}[/latex]
   c. [latex]\frac{2}{\sqrt{3}}[/latex]
   d. [latex]\sqrt{3}[/latex]
7. [2080 ‘R’] The given figure represents a wavefront AB moving in air and incident on a plane glass surface XY. Its position after refraction through the glass slab is CD. The refractive index of glass with respect to air will be equal to:

1. AB/CD                        
2. BD/AD                                
3. AC/AD                       
4. BD/AC

Answers

1.d

2.a

3.c

4.d

5.b

6.d

7.d

THEORETICAL QUESTIONS

New Course

1. [2082] State and prove Brewster’s law. [2]
2. [2081 ‘D’] State and prove Brewster ‘s Law. [2]
3. [2080 GIE ‘A’] What is meant by surface energy of a liquid? Write its relation with surface tension of the liquid. [2]

Old Course

SHORT ANSWER QUESTION

4. [2078 ‘C’] Is polarization possible for longitudinal waves? Explain.
5. [2077 ‘D’] Can sound waves be polarized? Explain.
6. [2076 GIE ‘A’] State Brewster’s law.
7. [2076 GIE ‘B’] Can sound wave be polarized? Justify your answer.
8. [2076 ‘B’] Differentiate unpolarized and polarized light.
9. [2076 ‘C’, 2074 ‘B’] Can sound waves be polarized? Explain.
10. [2075 ‘S’, 2075 ‘A’, 2074 ‘A’, 2073 ‘S’, 2072 ‘C’] What is polarizing angle? Does it depend on wavelength of light used?
11. [2075 ‘B’] Can ultrasonic waves be polarized?
12. [2072 ‘D’] What is polarized light? how is it represented?
13. [2073 ‘C’] Are light waves longitudinal? Justify your answer.
14. [2073 ‘D’] State and explain Brewster’s law of polarization.
15. [2072 ‘D’] What is polarized light? how is it represented?
16. [2072 ‘E’] Is polarization possible for longitudinal waves? Justify.

LONG ANSWER QUESTION

17. [2074 ‘S’]What is polarization of light? State and prove Brewster’s law.
    OR [2073 ‘D’] What is polarization? Prove that light is a transverse wave.

NUMERICAL PROBLEMS

New Course

1. [2079 GIE ‘A’] Calculate the polarizing angle for light travelling from water of refractive index 1.33 to glass of refractive index 1.53. [1] Ans: 49^o

Old Course

2. [2072 ‘S’]The polarizing angle for a medium is 60^o. Calculate the velocity of light in the medium. Ans: 1.73 x 10⁸ m/s
3. A beam of light is incident at polarizing angle on a piece of transparent material of refractive index 1.62. What is the angle of refraction for the transmitted beam? Ans: 31.65^o
4. The critical angle for light in a certain substance is 45^o. What is the polarizing angle? Ans: 54.7^o
5. Calculate the polarizing angle for the light travelling from water of refractive index 1.33 to glass of refractive index 1.53. Ans: 49^o
6. The polarizing angle for a transparent medium is 60^o. What is the refractive index of the medium? Ans: [latex]\sqrt{3}[/latex]
7. A parallel beam of unpolarized light in air is incident at an angle of 55^o on a plane glass surface. If the reflected beam is completely plane polarized, find the refractive index of the glass and the angle of refraction of the transmitted beam. Ans: 1.428, 35^o