Answers For Slip Test -3

I Answer the following Questions            10 x 1/2 = 5 m

1. Write Snell’s law.

A. n1 sini = n2 sinr or n1/n2 = sinr / sin i.

2. What is the reason behind the brilliance of diamond ?

A. Total internal reflection

3. What is the Speed of light in vacuum ?

A. 3 x 10 power 8 m / s.

4. What is the critical angle of diamond ?

A. 24.4 degrees

5. What is the reason behind the twinkling of stars ?

A. Atmospheric refraction.

6. write the unit of refractive index?

A. No units. It is a dimensionless quantity.

7. The refractive index of glass with respect to air is 2. Then the critical angle of glass-air interface is  

A) 0    B) 45   C) 30    D) 60 

A. 30 degrees (C).

8. Total internal reflection takes place when the light ray travels from

A) rarer to denser medium B) rarer to rarer medium 

C) denser to rarer medium D) denser to denser medium

A. Denser to rarer medium (C).

9. The angle of deviation produced by the glass slab is

A) 0    B) 20   C) 90   D) depends on the angle formed by the light ray and normal to the slab

A (D) depends on the angle formed by the light ray and normal to the slab

10. The distance between the parallel rays in a glass slab is called

A) Lateral shift B) Vertical shift C) Refractive index D) All

A) Lateral Shift (A).

II Answer the following Questions            4 x 2 = 8 m

12. The speed of the light in a diamond is 1,24,000 km/s. Find the refractive index of diamond if the speed of light in air is 3,00,000 km/s.

A.      Speed of light in air = 3,00,000 km/s

         Speed of light in a diamond = 1,24,000 km/s

        Refractive index  n = C / V 

                                        =300000/ 124000

                                        = 2.42

13. The refractive index of glass is 3/2. Then what is the speed of light in glass?

A. Refractive index of glass (n) = 3/2

    speed of light in vacuum (c) = 3×10 power 8 m/s.

                                        n = C / V

                                        V= C / n

                                          = 3 x 10 power 8/ 3/2

         Speed of light in glass V = 2 x 10 power 8 m/s.

  

14. Determine the refractive index of benzene if the critical angle is 42 ?

A. Critical angle of benzene(C) = 42

     Refractive index of benzene (n) = ?

     We know that n = 1 / Sin C

                        n = 1/ sin 42o

                           

                           = 1/ 0.6691

                           = 1.51

∴ Refractive index of benzene (n) = 1.51

15. Write the laws of refraction?

A. Laws of refraction:

1. The incident ray, the refracted ray and the normal all lie in the same plane.

2. During the refraction light follows Snell’s law.

n1 sin i = n2 sin r

III Answer the following Questions             3 x 4 = 12 m

16. Explain the formation of Mirage?

A. Mirage: Mirage is an optical illusion where it appears that water has collected on the road at a distant place but when we get there, we don’t find any water.

                                 

                                 

  

formation of mirage:

1. During a hot summer day, air just above the road surface is very hot and the air at higher altitudes is cool.

2. It means that the temperature decreases with height.

3. As a result density of air increases with height.

4. Light travels faster through the thinner hot air than through the denser cool air.

5. When the light from a tree or from the sky passes just above the road, it suffers, refraction and takes a

curved path because of total internal reflection.

6. This refracted light reaches the observer

7. Hence we feel the illusion of water being present on road which is the virtual image of the sky (mirage) and an inverted image of tree on the road.

17. How do you verify experimentally that sini / sinr is a constant?

                                  

          

    

18. Explain the refraction of light through glass slab with neat diagram?

A. Aim: Determination of refraction of light through a glass and lateral shift.

Material required:plank, chart paper, clamps, scale, pencil, thin glass slab and pins.

                                                    

Procedure:1. Place a glass slab in the middle of the paper and draw border line along the

2. You will get a figure of a rectangle. Name the vertices of the rectangle as

A, B, C and D.

3. Draw a perpendicular at a point on the longer side (AB) of the rectangle.

4. Now draw a line, from the point of

normal. This line represents the incident ray.

5. Now place the slab on the the rectangle drawn. Fix two identical pins on the

incident ray.

6. By looking at the two pins from the other side of the slab, fix two pins in such

a way that all pins appear to be along a straight line.

7. Remove slab and pins. Draw a straight line by joining the dots formed by the

pins up to the edge CD of the rectangle.

8. This line represents emergent ray of the light.

9. Draw a perpendicular ON to the line CD where where the line 'RS' meets the line 'CD'.

Result:1.The incident and emergent rays (PQ, RS) are parallel.

2. Measure the distance between the parallel rays (PQ, RS). This distance is called Lateral shift.

Tags: Answers, Sliptest -3, Refraction of light, Snell's law, Refraction, Sini / Sin r is  a constant.