Four students A, B, C and D were asked by their teacher to find the corresponding image distance for the given object distance keeping the object at various distance in case of a given convex lens of focal length 15 cm. The following observation were recorded by them.

Question

Philoid · Accepted Answer

Using lens formula:

For A: Object distance, u = -22.5 cm
Image distance, v = ?

v= = 45cm

Hence A’s observation is correct.

For B: Object distance, u = -25 cm
Image distance, v = ?

v= = 37.5cm

Hence B’s observation is wrong.

For C: Object distance, u = -37.5 cm
Image distance, v = ?

v= = 25cm

C’s observation is correct.

For D: Object distance, u = -45 cm
Image distance, v = ?

v= = 22.5 cm

D’s observation is also correct.