Question

2 concave lens each of focal length 30cm are placed in contact .what is focal length of the compound lens

Answer 1

Heya,

According to the question,

Focal length of two Concave lens = -30cm

We calculate the effective focal length by the formula,

1/F = 1/f1 + 1/f2

f1 = -30
f2 = -30

1/F = -1/30 - 1/30

1/F = -2/30

1/F = -1/15

F = -15

So, the focal length of the compound lens = -15cm

Hope this helps....:)

Answer 2

Explanation:

the focal length of the compound lens -15 cm