Home › NEET UG › Physics › Ray Optics and Optical Instruments › The lens-maker's formula for a thin lens (refrac…
The lens-maker's formula for a thin lens (refractive index n) with radii of curvature R₁ and R₂ is:
A1/f = (n − 1)(1/R₁ − 1/R₂)
B1/f = (n − 1)(1/R₁ + 1/R₂)
C1/f = n (R₁ + R₂)
D1/f = (n + 1)/R
Answer & Solution
Correct answer: A. 1/f = (n − 1)(1/R₁ − 1/R₂)
**Lens-maker's formula: 1/f = (n − 1)(1/R₁ − 1/R₂)** (thin lens in air; n = refractive index of lens material). Sign convention applies to R₁ and R₂. Used to design lenses or determine f from geometry/material.
Related questions
The phenomenon by which the apparent position of a star near the horizon appears slightly An object is placed at the FOCUS of a concave mirror ($u = f$, both negative). The image fWhen light travels from one medium to another, which property of the wave REMAINS UNCHANGELight passing through a PRISM is dispersed because different colours of light haveA converging lens of focal length $20\,\text{cm}$ produces a real image at $30\,\text{cm}$Optical fibres use TOTAL INTERNAL REFLECTION to transmit light over long distances. The MATwo thin lenses of powers $+5\,\text{D}$ and $-3\,\text{D}$ are placed in CONTACT. The totThe POWER of a lens (in diopters, D) is defined as