Optics 2 Question 15

15. A ray of light from a denser medium strikes a rarer medium at an angle of incidence i (see figure). The reflected and refracted rays make an angle of 90 with each other. The angles of reflection and refraction are r and r. The critical angle is (1983,1M)

(a) sin1(tanr)

(b) sin1(coti)

(c) sin1(tanr)

(d) tan1(sini)

Show Answer

Answer:

Correct Answer: 15. (a)

Solution:

  1. r+r+90=180

r=90r Further, i=r

Applying Snell’s law, μDsini=μRsinr

or μDsinr=μRsin(90r)=μRcosr

μRμD=tanr,θC=sin1μRμD=sin1(tanr)



NCERT Chapter Video Solution

Dual Pane