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

Correct answer: D. 0.08 For first lens m_1=(v)/(u)=(f)/(u+f)=(100)/(-50+100)=2 Image distance v=2 u=2 ×(-50)=-100 ~cm For second lens Now u=-190 ~cm, f=-8 ~cm, m_2= ? m_2=(v)/(u)=(f)/(u+f)=(-8)/(-190-8)=0.04 Net magnification =m_1 m_2=0.08

AIIMS 201827 May

Exam: AIIMS
Year: 2018
Date: 27 May
Subject: Physics
Chapter: Ray Optics

AIIMS 2018 · 27 May · Physics · Ray Optics

Focal length of convex lens is 100 ~cm and focal length of concave...

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

Focal length of convex lens is 100 ~cm and focal length of concave lens is 8 ~cm . Find the magnification of the given

Options

A $1.02$
B $0.04$
C $2.01$
D $0.08$

Correct answer

D. $0.08$

Step-by-step 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

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