Question

What is the focal length of a lens if an object placed 3.28 cm from the lens produces an image that is 1.91 cm in front of the lens?0.828cm-4.57cm-0.219cm1.21cm

Answer 1

Using lens equation:

`\begin{gathered} (1)/(f)=(1)/(d_i)+(1)/(d_o) \\ where: \\ di=1.91 \\ d_o=3.28 \\ so: \\ (1)/(f)=(1)/(1.91)+(1)/(3.28) \\ so: \\ f\approx1.21cm \end{gathered}`

Answer:

1.21 cm