Question

please give the answrs I need .....

Answer 1

distant object - tree , building , car , electricity pole etc.

distance between the lens and the screen for both the surface can be taken same let take it 21cm

( while doing experiment it may be different)

average f1 = 21

average f2 = 21

f= 21+21 / 2 = 21

conclusion

1. 21cm

2.f1 = f2

3. lens used is symmetric.

NOTE - focal length of every lens may be different.