Question

Draw ray diagrams showing the image formation by a convex lens when an object is placed

(a) between optical centre and focus of the lens
(b) between focus and twice the focal length of the lens
(c) at twice the focal length of the lens
(d) at infinity
(e) at the focus of the lens

Answer 1

(a) Object is between optical center and focus of the lens​ ​

1. When an object is placed in between focus and optical centre, a virtual image is formed.
2. The size of the image is larger than that of the object.

(b) Object is between focus and twice the focal length of the lens

1. When an object is placed in between the centre of curvature and focus, the real image is formed behind the centre of curvature.
2. The size of the image is larger than that of the object.

(c) Object is

at twice the focal length of the lens

1. When an object is at the centre of curvature, the real image is formed at the other centre of curvature.
2. The size of the image is the same as compared to that of the object.​

d) Object is

at infinity

1. When an object is placed at infinity, the real image is formed at the focus.
2. The size of the image is highly diminished and point size.

(e) Object is

at the focus of the lens

1. When an object is placed at the focus, a real image is formed at infinity.

2. The size of the image is much larger than that of the object.​