Question
The following data was recorded for values of object distance and the corresponding values of image distance in the experiment on study of real image formation by a convex lens of power +5D. One of these observations is incorrect. Identify this observation and give reason for your choice:
S .No
Object distance (cm)
Image distance (cm)
1
25
97
2
30
61
3
35
37
4
45
35
5
50
32
6
55
30

Answer

Power of lens = +5D
Focal length of lens,
The observations at serial number (3) i.e., (object distance 35cm and image distance 37cm is incorrect), because if the object is placed at a distance between f and 2f its image will be formed beyond 2f, while in this observation the object and image distances, both are between f and 2f.

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