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NEET 2012 (AIPMT, Prelims) · Spherical Surfaces & Thin Lenses

Spherical Surfaces & Thin Lenses question from NEET 2012 (AIPMT, Prelims)

Q100NEET 2012 · AIPMT · PRELIMSEasy

Spherical Surfaces & Thin Lenses

When a biconvex lens of glass having refractive index 1.47 is dipped in a liquid, it acts as a plane sheet of glass. This implies that the liquid must have refractive index

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Answer: (a)

  1. A lens acts as a plane sheet when f=∞f = \infty, i.e. 1f=(μgμl−1)(1R1−1R2)=0\frac{1}{f} = \left(\frac{\mu_g}{\mu_l} - 1\right)\left(\frac{1}{R_1} - \frac{1}{R_2}\right) = 0.
  2. This needs μl=μg=1.47\mu_l = \mu_g = 1.47.
  3. So the answer is (a) equal to that of glass.
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