ray diagram – object closer than 1f

This post is for Standard Grade and Intermediate 2.

Here we consider an object closer than one focal length.  You will see that it is not possible to obtain a real image when the object is this close to the lens.  On a ray diagram, a real image is one that is found on the other side of the lens from the object.

Real images can always be displayed on a screen – a projector in the cinema or classroom produces a real image.  If you are doing an experiment, you can check to see if an image is real using a piece of paper.  Move your sheet of paper closer to and further from the lens – if you can’t get an image to form on the paper then the image must be virtual.  When we look at an object up close through a magnifying glass, we see a virtual image.

ray diagram for objects closer than 1f from mr mackenzie on Vimeo.

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