An object 1.75 cm tall is placed 13.5 cm from a converging lens. A real image is formed 7.86 cm from the lens. image? What is the focal length of the lens? How tall is the image?

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Answer 1 · 2017-12-28T10:35:53

The focal length is #=5cm#. The height of the image is #=1.02cm#

The thin lens equation is

#1/d_o +1/d_i=1/f#

The distance of the object is #d_0=13.5cm#

The distance of the image is #d_i=7.86cm#

Therefore,

#1/f=1/13.5+1/7.86=0.201#

#f=1/0.201=4.97cm~=5cm#

The magnification is

#M=h_i/h_o=d_i/d_o#

#h_i=7.86/13.5*1.75=1.02cm#