MEASURE THE FOCAL LENGTH OF A CONVEX LENS
Determine the focal length of a convex lens with three different methods and make a comparison among them which one is the best.
A convex lens, lens holder, cardboard screen, optical bench consisting a meter stick mounted on supports, candle, grid paper, ruler
When an object is placed at a distance O from a convex lens with focal length f, then if O＞f, a real image is formed at some distance I away from the lens (see Figure 1). For O＜f, a virtual image is formed where I is negative. A real image can be focused onto a screen, whereas as a virtual image cannot. The relationship between these quantities is given by the thin lens equation.