a concave lens and concave lens of focal length +20cm and -30cm respectively then find the power of each lens find the focal length of combined lens and find the combined power of the lenses
Answers
Answered by
0
Answer:
Correct option is
C
+5D
Given: Two lens of focal length, f
1
=−20cm and f
2
=+10cm are put in combination
To find the power of the combination.
Solution:
If focal length of the combined lens is F
Use the formula,
F
1
=
f
1
1
+
f
2
1
⟹
F
1
=
(−20)
1
+
10
1
⟹
F
1
=
20
−1+2
⟹F=20cm=0.2m
So the power of the combination is,
P=
0.2
1
=+5D
Similar questions