Answer to Question #52743 in Optics for Atooki Yunus

Question

A camera obscura used by a potrait painter is located 6 m from a child who stands 1 m tall. How tall is her image if the back of the camera obscura is 2 m away?

1/3 m
1/2 m
1 m
3 m

Answer 1

The magnification of the camera obscura is given by
M=d_i/d_o ,
where d_i – is the image distance, and d_o – is the object distance. Therefore, the height of the image is
h_i=M∙h_o=d_i/d_o h_o
Since d_i=2m, d_o=6m, and h_o=1m, we obtain
h_i=d_i/d_o h_o=2m/6m 1m=1/3 m
Answer: 1/3 m.