A thin convex lens and a thin concave lens are kept in contact and are co-axial. Which of the following statements is correct for this combination of two lenses ?

Step-by-step solution

The equivalent focal length F of two thin lenses in contact is given by 1 F = 1 f₁ + 1 f₂ For a convex lens, the focal length is positive, so f₁ = |f_ convex | For a concave lens, the focal length is negative, so f₂ = -|f_ concave | Substituting these values, we get 1 F = 1 |f_ convex | - 1 |f_ concave | If |f_ convex | > |f_ concave | , then 1 |f_ convex | This implies 1 F A negative equivalent focal length indicates that the combination behaves as a diverging or concave lens. Interchanging the positions of the le