Physlet Illustration: Image Formation by a Convex Lens

 

 
In this simulation, an object is placed in front of a convex lens of focal length f = 0.5 cm.. The focal points are indicated both in front of and behind the lens. What are the characteristics of the images that may be formed by the lens?

Hints:

  1. Drag the object until it is more than one focal length away from the lens, to a position where you can clearly see the image formed on the opposite side of the lens.
  2. Is this a real or virtual image? Is it upright or inverted compared to the original object? Enlarged or reduced?
  3. Determine the object distance, do, and image distance, di. (These are measured from the center of the lens. Remember the sign conventions!)
  4. Do these quantities obey the thin-lens equation?
  5. Calculate the magnification. Does its value support your observations of the image characteristics?
  6. Now drag the object until it is less than one focal length away from the lens, to a position where you can clearly see the image formed on the same side of the lens.
  7. Repeat steps 2-5.

Reference

See The New Cosmic Universe, Section 31.4

Illustration written by Steve Mellema