The diameter of the eye-ball of a normal eye is about $2.5\, cm$. The power of the eye lens varies from

$A$ far-sighted man who has lost his spectacles reads a book by looking through a small hole $(3-4 \,mm)$ in a sheet of paper. The reason is:

$A$ person cannot see objects clearly placed at a distance of more than $40 \, cm$. He is advised to use a lens of power:

The sensation of vision in the retina is carried to the brain by

$A$ man cannot see clearly the objects beyond a distance of $20 \, cm$ from his eyes. To see distant objects clearly,he must use which kind of lenses and of what focal length?

$A$ student studying the similarities and differences between a camera and the human eye makes the following observations:
$I$. Both the eye and the camera have convex lenses.
$II$. In order to focus,the eye lens expands or contracts while the camera lens moves forward or backward.
$III$. The camera lens produces upside down real images while the eye lens produces only upright real images.
$IV$. $A$ screen in a camera is equivalent to the retina in the eyes.
$V$. $A$ camera adjusts the amount of light entering in it by adjusting the aperture of the lens. In the eye,the cornea controls the amount of light. Which of the above statements are correct?