The tricky lens

Classical Mechanics Level 3

A diverging (double concave) lens with a focal length of $5 \text{ m}$ is used to project an image of an object which was located $8 \text{ m}$ opposite the side of the lens containing the object.

What is the orientation of the image and how far is the object from the center of the lens?

The thin lens equation : $\dfrac {1}{d_o} + \dfrac {1}{d_i} = \dfrac{1}{f}$

Upside down; at

\frac{40}{13} \text{ m}

from the center of the lens Upside down; at

\frac{40}{3} \text{ m}

from the center of the lens This can never happen, so there's no answer to this question. Upright; at

\frac{40}{3}\text{ m}

from the center of the lens It cannot be determined due to the lack of information The distance of the object is negligible There is no object in this system Upright; at

\frac{40}{13} \text{ m}

from the center of the lens

1 solution

Efren Medallo
Aug 22, 2016

The thing is, a diverging lens always produces an image located on the same side where the object is located . Thus, given a physically impossible premise, there is no answer to this question.

The tricky lens

1 solution

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