Q130 / 180 · AIIMS 2018 (27 May) · Physics

Focal length of convex lens is $100 \mathrm{~cm}$ and focal length of concave lens is $8 \mathrm{~cm}$. Find the magnification of the given combination of lens if object is placed at point $O$. Figure

  • A
    $1.02$
  • B
    $0.04$
  • C
    $2.01$
  • Correct answer
    D
    $0.08$

Solution

For first lens $m_1=\frac{v}{u}=\frac{f}{u+f}=\frac{100}{-50+100}=2$ Image distance $v=2 u=2 \times(-50)=-100 \mathrm{~cm}$ For second lens Now $u=-190 \mathrm{~cm}, f=-8 \mathrm{~cm}, m_2=$ ? $m_2=\frac{v}{u}=\frac{f}{u+f}=\frac{-8}{-190-8}=0.04$ Net magnification $=m_1 m_2=0.08$

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

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