$A$ concave lens made of a material of refractive index $n_{1}$ is kept in a medium of refractive index $n_{2}$. $A$ parallel beam of light is incident on the lens. Complete the path of rays of light emerging from the concave lens if
$(i)$ $n_{1} > n_{2}$ $(ii)$ $n_{1}=n_{2}$ $(iii)$ $n_{1} < n_{2}$

(N/A) $(i)$ When $n_{1} > n_{2}$,the lens acts as a denser medium compared to the surroundings. Therefore,the concave lens behaves as a diverging lens,and the parallel rays diverge after passing through it.
$(ii)$ When $n_{1} = n_{2}$,the lens and the surrounding medium have the same refractive index. There is no change in the optical density,so the light rays pass through the lens without any deviation or refraction.
$(iii)$ When $n_{1} < n_{2}$,the lens acts as a rarer medium compared to the surroundings. In this case,the nature of the lens reverses,and the concave lens behaves as a converging lens,causing the parallel rays to converge after passing through it.