Q. Describe diffrent principle of rays?

Principle Ray I: The easy one it hits the lens smack dab in the middle as well as passes straight on through.

Principle Ray II: Preliminary on the object side of the lens ray II heads toward the plane of the lens along a line that is parallel to the principle axis of the lens. At the plane of the lens it suddenly adopts a path along a line that takes the ray through the focal point on the other side of the lens.

Principle Ray III: Preliminary from the head of the arrow that the object is ray III travels toward the plane of the lens along a line that passes through the focal point on the same side of the lens as the object. This ray passes by that focal point only if the object is farther from the lens than the focal point itself is. In any case ray III move toward the plane of the lens. At the plane of the lens the ray suddenly adopts a new path which is parallel to the principle axis of the lens.