Magnifying glasses - Higher

A magnifying glass is a convex lens used to make an object appear much larger than it actually is.

This works when the object is placed at a distance from the lens of less than one focal length. The image is:

  • on the same side of the lens as the object, but further away;
  • upright;
  • enlarged;
  • virtual.
Two light rays extend out from the object which is shown by a small green arrow that sits between F and the lens. The rays that extend to the image are in a lighter shade. Ray diagram for an object placed less than one focal length from a convex lens

Only the person looking through the magnifying glass can see the image.

The image cannot be projected onto a screen because it is a virtual image.

The table below summarises the nature of the images produced by a converging lens.

Distance of objectSizeOrientationTypePositionApplication
Further than 2FDiminishedInvertedRealBetween 2F and FThe eye or camera
2FSame sizeInvertedReal2F
Between 2F and FEnlargedInvertedRealFurther than 2FCinema projector
FNo image because the emerging rays are parallel to the axisSearchlight. Or follow spot in the theatre
Closer than FEnlargedUprightVirtualSame side as object but further awayMagnifying glass