Physics miscellaneousHard

Question

Light enters at an angle of incidence in a transparent rod of refractive index n. For what value of the refractive index of the material of the rod the light once entered into it will not leave it through its lateral face whatsoever be the value of angle of incidence :-

Options

A. n > √2
B.n = 1
C.n = 1.1
D.n = 1.3

Solution

    
From the following figure
r + 1 = 90o ⇒ i = 90o - r
For ray not to emerge from curved surface i > C
⇒ sini > sinC ⇒ sin(90o -r) > sinC ⇒ cosr > sinC
⇒        
⇒ 1 - ⇒ 1 > (1 + sin2α)
⇒   n2 > 1 + sin2α  ⇒ n > √2  {sini → 1}
⇒  Least value = √2

Create a free account to view solution

View Solution Free
Topic: Physics miscellaneous·Practice all Physics miscellaneous questions

More Physics miscellaneous Questions

-...A large glass slab of thickness 8 cm is placed over a point source of light on a plane surface. It is seen that light em...Buffer solutions have constant acidity and alkalinity because...If θi, is the inversion temperature, θn is the neutral temperature, θc is the temperature of the cold jun...A coil is self-inductance L is connected in series with a bulb B and an AC source. Brightness of the bulb decreases when...