- Draw a ray from point source (S) in
any direction to meet lens at point (PI ).
- Now draw another line parallel to the
ray drawn from the point source (S) such that it
passes through the optic centre (P); This line
intersects thenormal at point FO.
- Now draw a line passing from point Pl
to pass through the point FO
such that it meets principal axis at a point say (I).
- ‘I’ is the image point for the point source (S). Example 5
Complete the ray diagram to show
the paths of the rays after refraction
through the lenses shown in the
figures E5(a) and E5(b)?
Solution: Follow the steps
mentioned in Example (4) to complete the ray diagrams.
You will notice that the paths of the rays are shown in figures E5(c) and 5(d).
Can we realise in practice the results obtained in the ray diagrams
when we perform experiment.
Aim: Observing the types of images and measuring the object distance
and image distance from the lens. Material required: A candle, paper, convex lens (known focal length),
V-stand, measuring tape or meter scale. Procedure: Take a v-stand and place it on a long (nearly 2m) table
at the middle. Place a convex lens on the v-stand. Imagine the principal
axis of the lens. Light a candle and ask your friend to take the candle far
away from the lens along the principal axis. Adjust a screen (a sheet of
white paper placed perpendicular to the axis) which is on other side of the
lens until you get an image on it.
Why are we using a screen to view this image? Why don’t we see it
