A normal eye is not able to see objects closer than $25 \mathrm{cm}$ because :

Magnifying power of an astronomical telescope normal vision is

A man with normal vision uses a magnifying lens of focal length $10 \mathrm{cm}.$ Then

Write W for the incorrect statements and R for the correct ones:

The cones of human eye respond to strong light and cause sensation of colour and colour difference while the rods are sensitive to feeble light and movement of objects.

Write W for the incorrect statements and R for the correct ones:

Concave lenses are used to remedy long-sight defect and convex lens for short- sight defect.