Q 1 :    

Critical angle of incidence for a pair of optical media is 45°. The refractive indices of first and second media are in the ratio:           [2024]

  • 1:2

     

  • 1:2

     

  • 2:1

     

  • 2:1

     

(C)             We know

                  sinc=n2n1n1n2=1sinc

                  n1n2=1sin45=21

                   n1:n2=2:1

 



Q 2 :    

A light ray is incident on a glass slab of thickness 43 cm and refractive index 2. The angle of incidence is equal to the critical angle for the glass slab with air. The lateral displacement of ray after passing through glass slab is ____ cm.

(Given sin15o = 0.25)                               [2024]



(2)

i=θci=sin-1(1μ)

i=45°

According to Snell’s law,

1sin45°=2sinr12=2sinr12=2sinr

r=30°

Now, Δx=tsec30°sin15°=43×23×14=2 cm



Q 3 :    

Two immiscible liquids of refractive indices 85 and 32 respectively are put in a beaker as shown in the figure. The height of each column is 6 cm. A coin is placed at the bottom of the beaker. For near normal vision, the apparent depth of the coin is α4cm. The value of α is ____.         [2024]



(31)

happ=h1μ1+h2μ2=68/5+63/2=4+154=314 cm