PHYS112 : Web Resources

PHYS112 : Locating Virtual Images

A real image can be projected on a screen, so it is easy to measure its position. Measuring the position of a virtual image is more challenging, because a virtual image can only be seen by looking into the optical element that forms it. One way to determine the location a virtual image is to compare the parallax of the image to that of neighboring objects as illustrated by the animations below.

Too Far Away

The apparent displacement of the black marker is smaller than that of the virtual image of the red object, so the marker is farther away from you than the image.

Too Close

The apparent displacement of the black marker is smaller than that of the virtual image of the red object, so the marker is closer to you than the image.

Just Right

The apparent displacement of the black marker is the same as that of the virtual image of the red object, so the marker is at the position of the image.