A lens forms an erect, magnified and virtual image of an object.
Draw a labelled ray diagram to show the image formation.

We wish to obtain an erect image of an object, using a concave mirror of focal length 15cm what should be the range of distance of the object from the mirror? What is the nature of the image ? Is the image larger or smaller than object? Draw a ray diagram to show the image formation in this case.

The image of a candle is formed by a convex lens on a screen. The lower half of the lens is painted black to make it completely opaque. Draw the ray diargram to show the image formation. How will this image be different from the one obtained when the lens is not painted black?

………..froms virtual and same size of image of an object

By giving sign-conventions, derive the lens formula relating object distance, image distance and focal length for a thin convex lens. Draw a ray diagram to show the formation of image of an object placed between optical centre and focus of a convex lens.