A combination of two thin lenses in contact have power +10 D . The power reduces to +6 D when the lenses are 0.25 ~m apart. The power of individual lens is

Step-by-step solution

When in contact, the equivalent power of two thin lenses is, P ₁+ P ₂=10 When the lenses are separated by 0.25 ~m , P ₁+ P ₂-0.25 P ₁ P ₂=6 array ll & 0.25 P ₁ P ₂=4 & P ₁ P ₂=16 & P ₁- P ₂= ( P ₁+ P ₂ )^2+4 P ₁ P ₂ & P ₁- P ₂= 36 =6...(i) array Adding equations (i) and (ii), we get, aligned P ₁ & =8 D P ₂ & =10-8=2 D aligned