Optics Question 580

Question: A convex lens of focal length 40 cm is in contact with a concave lens of focal length 25 cm. The power of combination is

[IIT-JEE 1982; AFMC 1997; CBSE PMT 2000; RPMT 2003]

Options:

A) - 1.5 D

B) - 6.5 D

C) + 6.5 D

D) + 6.67 D

Show Answer

Answer:

Correct Answer: A

Solution:

Focal length of the combination can be calculated as 1F=1f1+1f2

1F=1(+40)+1(25)

F=2003cm

P=100F=100200/3=1.5 D



NCERT Chapter Video Solution

Dual Pane