What is the focal length of the eye-lens system when viewing an object at infinity? Assume that the lens-retina distance is 2.0 cm . Follow the sign conventions. Express your answer using two significant figures and include the appropriate units.

Focal length of the eye-lens is 2.0 cm

Explanation:

Given:

An eye-lens system which will follow converging lens (convex lens) sign conventions and knowing that lens-retina distance is the image distance.

Object distance, =

Image distance, = cm

We have to find the focal length.

Lets say that the focal length is .

Lens Formula:

⇒

Sign-convention:

We will follow the Cartesian coordinate,placing the lens at the origin of the plane, optical center is at now as the object will be towards negative x-axis so it is negative others are on the right side of the origin so they are positive.

Using the lens formula:

⇒

⇒      

⇒         ...as and there is no so it is zero only.

⇒ cm

So the focal length is 2.0 cm with two significant figures.