Page 19 - 10-phy-12 Geometrical Optics

Observed L O
image Lens

Eye
Search
pin

0 10 20 30 40 50 60 70 80 90 100

QP

Fig. 12.5.3

Materials A convex lens installed in a lens holder with base, two needle uprights and optical
Required bench.

Procedure 1. Get an image of a window or any distant object through the given convex
lens on the opposite wall of the laboratory.

2. Measure the distance between the lens and the image. This distance is
the approximate focal length (fa) of the lens.

3. Place the lens upright in the middle of the optical bench.

4. Fix a piece of paper on one of the needle uprights. Label this needle as
the object needle O. Place this needle upright in front of the lens at a
distance of more than one focal length.

5. Place the second needle upright on the other
side of the lens and label it as image needle I.

6. Look for the image of the object needle from Why should the object

the other side of the lens. This image will be needle be placed at more

inverted. than one focal length away

7. Adjust the position of the image needle to from the lens?

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