Question

A hollow lens is made of thin glass and in the shape of a double concave lens. It can be filled with air, water of refractive index $1.33$ or $C{S}_2$ of refractive index $\mathrm{1.6.}$ It will act as a diverging lens, if it is

• A. filled with air and immersed in water
• B. filled with water and immersed in $C{S}_2$
• C. filled with air and immersed in $C{S}_2$
• D. filled with $C{S}_2$ and immersed in wa

Answer 1

Answer: (D)

When medium outside a lens is denser than medium of lens, then a concave lens will acts like a convex lens and vice-versa. Now, when hollow lens is filled with $C{S}_2(\eta =16)$ and immersed in water $(p=133),$ its nature remains diverging as refractive index of medium of lens is more than refractive index of surrounding medium.