What is Focal Length ?

 What is focal point?

When light falls on a lens it focuses the rays of light at a point on other side of lens called as focal point.

When the Light source is distant so that parallel rays of light strike the Lens, a convex lens will focus these rays at a specific point, the focal point

Our eye is having Concave or Convex Lens?

Ans. Convex lens that focusses refracted light rays on Retina of our eyes and produces a image.