74
1 1 1
1
2
s s
f
+ =
Image formed by convex lens depends on distance of the object from the lens.
Figures 2.18, 2.19, 2.20, 2.21, 2.22, and 2.23 depict line diagrams of image formation by convex lens when the object is placed at different locations.
2.5.11 Chromatic Dispersion
The change in speed of light as it travels from one medium to another causes the
light to be refracted. The degree of bending depends on the angle of incidence as
well as the refractive indices of the media.
The refractive indices of many materials differ with the wavelength of the light,
which causes light of various colors to be refracted differently.
Chromatic dispersion is a phenomenon by which different spectral components
of light travel at varied velocities. Chromatic dispersion results in separation of
colors in a prism (Fig. 2.24) and chromatic aberration in lenses.
Focal Plane
Focal Point
f
Focal Length
Fig. 2.17 A simple
convex lens
Object
f
f
f
f
S 1
S 2
Image
Fig. 2.18 Line diagram showing the object between f and 2f
2 Fundamentals of Physics for Environmental and Medical Professionals