The absolute refractive indices of glass and water are \(\frac{3}{2}\) and \(\frac{4}{3}\) respectively. The refractive index at the interface when a ray travels from water to glass is

A.

\(\frac{1}{2}\)

B.

\(\frac{8}{9}\)

C.

\(\frac{9}{8}\)

D.

\(\frac{17}{12}\)

E.

2

Correct answer is C

Ray travelling from water to glass;

\(\frac{\text{speed of light in air}}{\text{speed of light in glass}}\) = \(\frac{3}{2}\)

= 3 x 108ms-1

X = 2 x 108ms-1

\(\frac{\text{speed of light in air}}{\text{speed of light in water}}\) = \(\frac{4}{3}\)

= \(\frac{3 \times 10^8}{g}\)

Y = 2.25 x 108ms-1

from water to glass;

Refractive = \(\frac{\text{speed of light in water}}{\text{speed of light in glass}}\)

= \(\frac{2.25 \times 10^8}{2.00 \times 10^8}\)

= 1.125

= \(\frac{9}{8}\)