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JEE Main 2022 (26 Jul, Shift 1) · Spherical Surfaces & Thin Lenses

Spherical Surfaces & Thin Lenses question from JEE Main 2022 (26 Jul, Shift 1)

Q67JEE Main 2022 · 26 JUL · SHIFT 1Medium

Spherical Surfaces & Thin Lenses

The graph between 1u\frac{1}{u} and 1v\frac{1}{v} for a thin convex lens in order to determine its focal length is plotted as shown in the figure. The refractive index of lens is 1.51.5 and its both the surfaces have same radius of curvature RR. The value of RR will be ____________ cm.\text{cm.} (where u=u = object distance, v=v = image distance)

Figure

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

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Answer: 10

  1. 1v−1u=1f\frac{1}{v} - \frac{1}{u} = \frac{1}{f}: at 1u=0\frac{1}{u} = 0, 1v=1f=0.10 cm−1\frac{1}{v} = \frac{1}{f} = 0.10\text{ cm}^{-1}, so f=10f = 10 cm.
  2. Equiconvex lens: 1f=(μ−1)2R=0.5×2R=1R\frac{1}{f} = (\mu - 1)\frac{2}{R} = 0.5 \times \frac{2}{R} = \frac{1}{R}
  3. R=f=10R = f = 10 cm
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