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JEE Main 2026 (6 Apr, Shift 1) · Spherical Surfaces & Thin Lenses

Spherical Surfaces & Thin Lenses question from JEE Main 2026 (6 Apr, Shift 1)

Q5JEE Main 2026 · 6 APR · SHIFT 1Medium

Spherical Surfaces & Thin Lenses

A spherical interface lens of radius RR separates two media of refractive indices 1 and 1.4 respectively as shown in the figure below. A point source is placed at a distance of 4R4R in front of spherical interface. The magnitude of the magnification of point source image is ______.

Figure

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Answer: (a)

  1. μ2v−μ1u=μ2−μ1R\frac{\mu_2}{v} - \frac{\mu_1}{u} = \frac{\mu_2 - \mu_1}{R} with u=−4Ru = -4R, centre in the denser side so R>0R > 0.
  2. 1.4v+14R=0.4R⇒1.4v=0.15R⇒v=28R3\frac{1.4}{v} + \frac{1}{4R} = \frac{0.4}{R} \Rightarrow \frac{1.4}{v} = \frac{0.15}{R} \Rightarrow v = \frac{28R}{3}
  3. m=μ1vμ2u=28R/31.4×(−4R)=−53m = \frac{\mu_1 v}{\mu_2 u} = \frac{28R/3}{1.4 \times (-4R)} = -\frac{5}{3}
  4. So the answer is (a) 1.66.
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