Question

Approximating the eye as a single thin lens 2.70 cmcm from the retina, find the focal length of the eye when it is focused on an object at a distance of 265 cmcm

Answer 1

Answer:

0.37 cm

Explanation:

The image is formed on the retina which is at a constant distance of 2.70 cm to the lens. Therefore, image distance = 2.70 cm.

The object is at a distant of 265 cm to the lens of the eye.

From lens formula,

$\frac{1}{f}$ = $\frac{1}{u}$ + $\frac{1}{v}$

where: f is the focal length, u is the object distance and v is the image distance.

Thus, u = 265.00 cm and v = 2.70 cm.

$\frac{1}{f}$ = $\frac{1}{265}$ + $\frac{27}{10}$

  = $\frac{10+7155}{2650}$

$\frac{1}{f}$  = $\frac{7165}{2650}$

⇒ f = $\frac{2650}{7165}$

      = 0.37

The focal length of the eye is 0.37 cm.