Loading....
Coupon Accepted Successfully!

 

Image Formation by Lenses

Drawing of Ray Diagrams for Lenses
Convex and concave lenses produce images. We can determine the position, size and nature (real or virtual, inverted or erect) of the image by drawing the ray diagrams. We take at least two rays diverging from any point on the object. Wherever they actually meet (or appear to meet) after refraction through the lens, is the real (or virtual) image of that point. In this manner taking one point on the object after another, the entire image of the object is constructed. Out of the possible infinite number of rays diverging from any point of the object, any two of the following three are the most convenient rays to use.

 

Images Formed by a Convex Lens
 

Images Formed by a Convex Lens for Various Positions of the Object on the Principal Axis

Position of the Object

Position of the Image

Nature of the Image

Size of Image Compared to that of the Object

Between 0 and F'

Behind the object

Virtual erect

Magnified

At F'

At infinity

Real inverted

High magnified

Between F' and 2F'

Beyond 2F

Real inverted

Magnified

At 2F'

At 2F

Real inverted

Same size as the object

Beyond 2F'

Between F and 2F

Real inverted

Diminished

At infinity

At F

Real inverted

Highly diminished


Images Formed by a Concave Lens
The image formed by a concave lens is always virtual for any position of the object.


1. Object at Infinity
The given figure shows the image formation when the object is at infinity. The rays coming from the top of the objects (not shown in the figure) are parallel. After refraction they appear to diverge from A' at the focal plane of the lens. The image is virtual, highly diminished and on the same side as the object.

 

2. Object at Any Other Position
The given figure shows the image of an object placed at a finite distance from the lens. The image is virtual, diminished and on the same side of the lens as the object.

 





Test Your Skills Now!
Take a Quiz now
Reviewer Name