This applet shows you how the position and type of image change depending on the position of the object and type of lens/mirror.

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Type of Lens / MirrorObjectImage
Convex Lens, Concave Mirrorfurther than 2Freal, inverted, diminished
at 2Freal, inverted, same size
between F & 2Freal, inverted, magnified
at Fat infinity
nearer than Fvirtual, upright, magnified
Concave Lens, Convex Mirroranywherevirtual, upright, diminished

The distances of the object and image from the lens/mirror are related by the lens formula: 1/u + 1/v = 1/f

where u = distance of object from the lens/mirror,
v = distance of image from the lens/mirror,
f = focal length of the lens/mirror.

If v is positive, the image is real and on opposite side of the lens from the object.
If v is negative, the image is virtual and on same side of the lens as the object.
f is positive for a convex lens or concave mirror.
f is negative for a concave lens or convex mirror.

Right-click here to download this page and the Java Class File.