A point object is placed in front of two thin coaxial convex lenses L₁ and L₂ of focal lengths 24 cm and 9 cm. Their separation is 10 cm and the object is 6 cm to the left of L₁. The distance between the object and the final image is ______ cm. Image
Physics · Circular Motion
JEE Mains 10 April 2023 Shift 2 Evening Shift

Question

A point object is placed in front of two thin coaxial convex lenses L₁ and L₂ of focal lengths 24 cm and 9 cm. Their separation is 10 cm and the object is 6 cm to the left of L₁. The distance between the object and the final image is ______ cm. Image

Physics · Circular Motion

JEE Mains 10 April 2023 Shift 2 Evening Shift

G1 Physics · Accepted Answer

For lens L₁: u₁ = −6 cm f₁ = +24 cm Using 1/f = 1/v − 1/u, 1/24 = 1/v₁ + 1/6 Therefore, 1/v₁ = 1/24 − 1/6 = −3/24 = −1/8 So, v₁ = −8 cm Thus the first lens forms a virtual image 8 cm to the left of L₁. Lens L₂ is 10 cm to the right of L₁, so for L₂ the object distance is u₂ = −(8 + 10) = −18 cm For lens L₂: f₂ = +9 cm 1/9 = 1/v₂ + 1/18 Therefore, 1/v₂ = 1/18 v₂ = 18 cm The final image is 18 cm to the right of L₂. Since L₂ is 10 cm to the right of L₁ and the original object is 6 cm to the left o…