Question

If $V_g,V_w$ and $V_d$ represent the velocities of light in glass, water and diamond respectively, then:

• A. $V_g<V_d<V_w$
• B. $V_w>V_g>V_d$
• C. $V_d>V_g>V_w$
• D. $V_w<V_g<V_d$

Answer 1

The correct option is B $V_w>V_g>V_d$

Given, $v_g$, $v_w$, $v_d$ represent the velocities of light in glass, water and diamond respectively.

So, if $v_a$ be the velocity of light in air, then we can say,

$v_g=\frac{v_a}{n_g}$, $v_w=\frac{v_a}{n_w}$, and, $v_d=\frac{v_a}{n_d}$.

Where, $n_g$, $n_w$, and $n_d$ are the refractive indices of glass, water and diamond respectively.

Now, we know, the refractive indices of glass, water and diamond are $1.5$, $1.33$, and $2.4$ respectively.

$\therefore n_w<n_g<n_d$.

So, from the above formulae, we have,

$n_w>n_g>n_d$

Therefore, the correct option is - (B) $n_w>n_g>n_d$.