Question

Two thin converging lens of focal length 0.15m and 0.30m are held in content with each other calculate the power and focal length​

Answer 1

Answer:

Explanation:1/F=1/f1+1/f2

Converging lens focal length =(+)ve

1/F=1/0.15+1/0.30

1/F=100×(1+2/30)

1/F=10m

F=0.10m

P=1/F=+10D

Answer 2

Formula:

The formula for the focal length, F (Combined) is given by :

                                           $\frac{1}{F} = \frac{1}{f1} + \frac{1}{f2}$

Where f1 is the focal length of first mirror and f2 is the focal length of the second mirror.

The formula for Power, P is given by:

                     P= $\frac{1}{F}$

Given:

f1 = 0.15 m

f2 = 0.30m

Putting the values of f1 and f2 in the above equation of focal length:-

   $\frac{1}{F} = \frac{1}{0.15} + \frac{1}{0.30}$

   $\frac{1}{F} = 10$

    F= 0.1 m

Power, P = $\frac{1}{F}$

P = $\frac{1}{0.1}$

P = 10 dioptre (D).

Hence, The Focal length and the power of the lens are 0.1 m and 10 D respectively.