JEE Main202522 Jan 2025Morning ShiftPhysicsRay OpticsActual
In the diagram given below, there are three lenses formed. Considering negligible thickness of each of them as compared to |R₁ | and |R₂ | , i.e., the radii of curvature for upper and lower surfaces of the glass lens, the power of the combination is
Options
- A1 6 ( 1 | R ₁ | - 1 | R ₂ | )
- B- 1 6 ( 1 | R ₁ | + 1 | R ₂ | )
- C1 6 ( 1 |R₁ | + 1 |R₂ | )
- D- 1 6 ( 1 | R ₁ | - 1 | R ₂ | )
Correct answer
D. - 1 6 ( 1 | R ₁ | - 1 | R ₂ | )
Step-by-step solution
aligned & p_ eq = p ₁+ p ₂+ p ₃ & p ₁= ( 4 3 -1 ) ( 1 - 1 - | R ₁ | ) & p ₁= ( 1 3 | R ₁ | ) & p ₂= ( 1 2 ) ( 1 - | R ₁ | - 1 - | R ₂ | ) & p ₂= 1 2 ( 1 | R ₂ | - 1 | R ₁ | ) & p ₃= ( 1 3 ) ( 1 - | R ₂ | - 1 )=- 1 3 | R ₂ | & p _ eq = 1 3 ( 1 | R ₁ | - 1 | R ₂ | )- 1 2 ( 1 | R ₁ | - 1 | R ₂ | ) & =- 1 6 ( 1 | R ₁ | - 1 | R ₂ | ) aligned