question_answer

An air bubble in sphere having 4 cm diameter appears 1 cm from surface nearest to eye when looked along diameter. If amg = 1.5, the distance of bubble from refracting surface is [CPMT 2002]

A)            1.2 cm                                     

B)            3.2 cm

C)            2.8 cm                                     

D)            1.6 cm

Correct Answer: A

Solution :

                   v = 1 cm, R = 2 cm By using \[\frac{{{\mu }_{2}}}{v}-\frac{{{\mu }_{1}}}{u}=\frac{{{\mu }_{2}}-{{\mu }_{1}}}{R}\] \[\frac{1}{-1}-\frac{1.5}{u}=\frac{1-1.5}{-2}\] \[\Rightarrow u=-1.2\,cm\]