Convex Lens Focal Length

Materials Required


The Procedure

Real Lab Procedure

  • Place a thin convex lens vertically on a lens holder kept on a table. The lens should face a distant object outside the window (a tree or an electricity pole or a distant building).
  • Place a screen fixed on a stand on the other side of the lens. Move the screen back and forth to obtain a sharp, clear and inverted image of the distant object.
  • Measure the distance between the screen and the optical centre of the convex lens using a measuring scale. Record the observation as the focal length of the lens.
  • Repeat the experiment at least 3 times and record it in the observation table.
  • Find the mean value of focal length.



Sl No Name of the distant object Distance between the convex lens and the screen (f) Mean focal length of the convex lens, f



The focal length of the given convex lens is _________.