When a biconvex lens of glass having refractive index `1.47` is dipped in a liquid, it acts as a plane sheet of glass. This implies that the liquid must have refractive index.

Options

A. equal to that of glass
B. less than one
C. greater that that of glass
D. less than that of glass

Answer

A

Explanation

According to lens maker.s formula
`(1)/(f)=((mu_(g))/(mu_(L))-1)((1)/(R_(1))-(1)/(R_(2)))`
where `mu_(g)` is the refractive index of the material of the lens and `mu_(L)` is the refractive index of the liquid in which lens is dipped. As the biconvex lens dipped in a liquid acts as a plane sheet of glass, therefore
`f=ooimplies(1)/(f)=0,:.(mu_(g))/(mu_(L))-1=0 "or" mu_(g)=mu_(L)`