Question

A thin symmetrical double convex lens of refractive index µ₂ = 1.5 is placed between a medium of refractive index µ₁ = 1 4. to the left and another medium of refractive index µ₃ = 1 6. to the right. Then, the system behaves as

(a) a convex lens

(b) a concave lens

(c) a glass plate

(d) a convex or concave lens

Answer 1

Answer is : (c) a glass plate

For first refracting surface,

For parallel beam of light,

v = 15R

For second refracting surface,

Hence, the combination behaves as a glass plate.