Question
A student was asked by his teacher to find the image distance for various object distances in case of a given convex lens. He performed the experiment with all precautions and noted down his observations in the following table:
|
S.No |
Object distance (cm) |
Image distance (cm) |
|
1 |
60 |
15 |
|
2 |
48 |
16 |
|
3 |
36 |
21 |
|
4 |
24 |
24 |
|
5 |
18 |
36 |
|
6 |
16 |
48 |
After checking the observation table the teacher pointed out that there is a mistake in recording the image distance in one of the observations. Find the serial number of observations having faulty image distance.
-
2
-
3
-
5
-
6
Solution
B.
3
The correct option is B.
In observation No. 3 the focal length comes out to be 13.26 cm whereas, the focal length for all other observation is 12 cm.
