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JEE Main 2026 (22 Jan, Shift 1) · Spherical Surfaces & Thin Lenses

Spherical Surfaces & Thin Lenses question from JEE Main 2026 (22 Jan, Shift 1)

Q6JEE Main 2026 · 22 JAN · SHIFT 1Medium

Spherical Surfaces & Thin Lenses

A parallel beam of light travelling in air (refractive index 1.0) is incident on a convex spherical glass surface of radius of curvature 50 cm. Refractive index of glass is 1.5. The rays converge to a point at a distance x cmx\text{ cm} from the centre of the curvature of the spherical surface. The value of xx is ______ cm.

Numerical answer type. Work it out, then open the answer.

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Answer: 100

  1. Parallel beam, u=∞u = \infty: μ2v=μ2−μ1R\frac{\mu_2}{v} = \frac{\mu_2 - \mu_1}{R}.
  2. v=1.5×500.5=150v = \frac{1.5 \times 50}{0.5} = 150 cm from the pole.
  3. Centre of curvature is 50 cm from the pole, so x=150−50=100x = 150 - 50 = 100.
  4. So x=100x = 100 cm.
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