Considering normal incidence of ray, the equivalent refractive index of combination of two slabs shown in figure is:

Question

Considering normal incidence of ray, the equivalent refractive index of combination of two slabs shown in figure is: (A) 1.8 (B) 1.43 (C) 2 (D) none of these

Tardigrade Admin · Accepted Answer

The equivalent refractive index of combination of slabs for normal incidence is

μ = \frac{Σ t _{i}}{Σ \frac{t _{i}}{μ _{i}}}

In this case,

μ = \frac{t _{1} + t _{2}}{\frac{t _{1}}{μ _{1}} + \frac{t _{2}}{μ _{2}}}

= \frac{10 + 15}{\frac{10}{4/3} + \frac{15}{3/2}}

= \frac{25}{7.5 + 10} = \frac{25}{17.5}

= 1.43

Q. Considering normal incidence of ray, the equivalent refractive index of combination of two slabs shown in figure is:

1.8

1.43

2

none of these

The equivalent refractive index of combination of slabs for normal incidence is μ=Σμi​ti​​Σti​​ In this case, μ=μ1​t1​​+μ2​t2​​t1​+t2​​ =4/310​+3/215​10+15​ =7.5+1025​=17.525​ =1.43