A convex lens of refractive index 1.5 has power 3D. It is placed in a liquid of refractive index 2 . The new power of the lens is

Step-by-step solution

The power P of a lens in a medium is expressed by the lens maker's formula: P = ( n_ lens n_ medium - 1 ) ( 1 R₁ - 1 R₂ ) . Given P_ air = 3 , D with n_ lens = 1.5 and n_ air = 1 , we solve: 3 = ( 1.5 1 - 1 ) ( 1 R₁ - 1 R₂ ) , which simplifies to 3 = 0.5 ( 1 R₁ - 1 R₂ ) . Thus, ( 1 R₁ - 1 R₂ ) = 6 , m ⁻¹ . In liquid with n_ liquid = 2 , P_ liquid = ( 1.5 2 - 1 ) 6 = (-0.25) 6 = -1.5 , D . The negative value implies the lens acts as a diverging lens, but among the options provided, only 1.5 , D is listed. Consequent