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JEE Main 2026 (28 Jan, Shift 2) · Combination of Lenses

Combination of Lenses question from JEE Main 2026 (28 Jan, Shift 2)

Q10JEE Main 2026 · 28 JAN · SHIFT 2Medium

Combination of Lenses

A biconvex lens is formed by using two thin planoconvex lenses, as shown in the figure. The refractive index and radius of curved surfaces are also mentioned in figure. When an object is placed on the left side of lens at a distance of 30 cm from the biconvex lens, the magnification of the image will be:

Figure

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Answer: (a)

  1. P=1.5−115+1.2−112=130+160=120⇒f=20 cmP = \frac{1.5-1}{15} + \frac{1.2-1}{12} = \frac{1}{30} + \frac{1}{60} = \frac{1}{20} \Rightarrow f = 20\text{ cm}
  2. u=−30u = -30: 1v=120−130=160⇒v=60 cm\frac{1}{v} = \frac{1}{20} - \frac{1}{30} = \frac{1}{60} \Rightarrow v = 60\text{ cm}
  3. m=vu=60−30=−2m = \frac{v}{u} = \frac{60}{-30} = -2
  4. So the answer is (a) −2-2.
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