• # question_answer Consider slabs of three media A, B and C arranged as shown in figure. R.I of A is 1.5 and that of C is 1.4. If the number of waves in A is equal to the number of waves in the combination B and C then refractive index of B is- A) 1.4                               B) 1.5C) 1.6                   D) 1.7

${{n}_{A}}={{n}_{B}}+{{n}_{C}}$ ${{\mu }_{A}}{{d}_{A}}\,=\,{{\mu }_{B}}{{d}_{B}}+{{\mu }_{C}}{{d}_{C}}$ $1.5\,(3x)=(x)\,\,+\,\,1.4\,(2x)$ $4.5\,\,=\,\,{{\mu }_{B}}\,\,+\,\,2.8$ ${{\mu }_{B}}=4.5-2.8\text{ }=1.7$