Question

two convex lensses of focal length 20cm each are placed in contact the net focal length of the combination will be
40cm
0.1cm
10cm
30cm
choose any one

Answer 1

Hii. Dear.

Here u are. ..

F1=20 =F2

Hence

1/f= 1/10

Then f= 10 ..

Thxx ..

It's hp here

Answer 2

two convex lensses of focal length 20cm each are placed in contact the net focal length of the combination will be

40cm

0.1cm

10cm

30cm

choose any one

Answer:

40cm