Question

This is pertaining to a lab using a convex lens with focal length 7.5 cm:

a) Set the object distance to an approximate value of 5cm. Move the white Viewing Screen along the optical bench. Are you able to see an image on the Viewing Screen? Explain why or why not conceptually.

b) Is it theoretically possible to create a non-inverted image with a converging spherical lens? Explain.

c) For the lens that was used in the first portion of the experiment, where would you need to theoretically place the object in order to create an image that is as far away from the lens as possible? How “large” would this image be?

Answer 1

a) The focal length of the lens is 7.5 cm and object is kept at 5 cm. Hence object is located between the optical center and the focus, so the image formed will be virtual. A virtual image cannot be taken on a screen so we will not be able to see an image on the screen for this case.

b) It is not possible to create a non- inverted image using a single convex lens on screen, because a non-inverted image will be virtual and cannot be taken on screen. However, if we use more than one lens we can have an anon-inverted image on a screen. Moreover, our brain can form a virtual image on our retina so with the human eye it is possible to form a non-inverted image.

c) The object must be placed at the focus of the lens because when the object is kept at focus the image is formed at infinity. This image will be very large compared to the size of the object may be 4 to 5 times more size.