ICSE Class 10 Answered

Complete the ray diagram in the case given below to show the formation of the image.  

Find the position, nature and focal length of the lens.

Answer:

Connect the tip of Image A'I to the tip of object AO so that point of the intersection on the principle axis gives the optical centre O' of the lens. Now  draw a ray AB starting from the tip of the object AO and parallel to the principle axis. This ray AB after refraction through lens should pass from the principle focus. Hence we draw ray BF. Now retrace the rays O'A and FB to make it meet at the point A'. When we look from the right side, it appears as if the ray is coming from A' and I instead of A and O.

Thus A'I is virtual image. It is erect, larger than the object. Hence when the object is palced within the focus of a convex lens, the image is formed is:

1. behind the object

2. virtual and erect

3. magnified