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JEE Main 2026 (4 Apr, Shift 2) · Spherical Surfaces & Thin Lenses

Spherical Surfaces & Thin Lenses question from JEE Main 2026 (4 Apr, Shift 2)

Q1JEE Main 2026 · 4 APR · SHIFT 2Easy

Spherical Surfaces & Thin Lenses

A convex lens is made from glass material having refractive index of 1.4 with same radius of curvature on both sides. The ratio of its focal length and radius of curvature is ______.

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Answer: (d)

  1. Equiconvex lens: 1f=(μ−1)2R\frac{1}{f} = (\mu - 1)\frac{2}{R}
  2. 1f=0.4×2R=0.8R\frac{1}{f} = 0.4 \times \frac{2}{R} = \frac{0.8}{R}
  3. fR=10.8=1.25\frac{f}{R} = \frac{1}{0.8} = 1.25
  4. So the answer is (d) 1.25.
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