Q82 / 120 · VITEEE 2019 · Physics

Two thin lenses are in contact and the focal length of the combination is $80 \mathrm{~cm}$. If the focal length of one lens is $20 \mathrm{~cm}$, then the power of the other lens will be

  • A
    $1.66 \mathrm{D}$
  • B
    $4.00 \mathrm{D}$
  • C
    $-100 \mathrm{D}$
  • Correct answer
    D
    $-3.75 \mathrm{D}$

Solution

$\mathrm{P}_{2}=\mathrm{P}-\mathrm{P}_{1}=\frac{100}{80}-\frac{100}{20}=-3.75 \mathrm{D}$

Hence, the correct answer is option: 'D'.

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