Page 203 - Physics_Form_2

Refraction and dispersion of light

Note: The image of an object can be
obtained by drawing any two of the ray
O diagrams.
O
F 1 F 2
Activity 5.12
FOR ONLINE READING ONLY
Aim: To determine the locations
(a) and characteristics of

images formed by a convex
lens for various object

O positions
F F Materials: graph paper, sharp pencil,
1 1
ruler, computer or tablet
with simulation software,
(b)
spreadsheet software
Figure 5.37: Refraction of light rays
incident through the Procedure
principal focus 1. Choose an appropriate scale so that
the ray diagrams fits on the available
Like in the case of spherical mirrors, space on the graph paper.
any two of the light rays are enough to 2. Draw a convex lens at the centre of
locate the image formed by a lens. The the graph paper.
refraction of light produced by a lens is
treated as occurring at a plane through the 3. Draw a horizontal line passing
through the optical centre of the lens.
optical centre, that is, perpendicular to the This is the principal axis.
principal axis of the lens. Whenever rays
diverge after passing through the lens, 4. Locate the points , 2 ,F 1 FF 2 , and 2F 2
1
on the principal axis as shown in
they are extended backwards to locate the Figure 5.38. Choose the focal point
virtual images. such that there is a considerable
distance between the optical centre,
Images formed by a convex lens O and the point 2F .
1
The location and characteristics of 5. Using the chosen scale, draw an
images formed by a convex lens vary upright arrow at a point beyond
depending on the position of the object 2F point.
1
relative to the optical centre of the lens. 6. Choose a point at the head of the
One can determine the characteristics of object arrow and draw a light
images formed by a convex lens when ray from this point parallel to the
the object is placed at various locations principal axis. Refract this ray
relative to the optical centre of the lens by
performing Activity 5.12. according to the rules of refraction.

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Physics Form 2 Final.indd 197 25/10/2025 10:28