Determine the optical power of the collecting lens if its focal length is 30 cm.

So, we need to determine the optical power of a collecting lens, if we know that its focal length is 30 cm.

Let’s start with a short note of the problem statement:

F = 30 cm.

D -?

Solution:

Let’s start the solution by converting the distance from centimeters to meters:

30 cm = 30: 100 = 0.3 meters.

Next, we will use the thin lens formula:

1 / d + 1 / f = 1 / F = D;

where D is the optical power,

F – focus.

We’ll apply the last part of the formula:

D = 1 / F;

Substitute values and perform calculations:

D = 1 / 0.3 = 3.3 diopters.