What is the magnification of the lens. If the distance from the object to the lens is 5 cm

What is the magnification of the lens. If the distance from the object to the lens is 5 cm, and from the lens to the image is 20 cm? Determine the focal length of this lens and its optical power.

To determine the focal length F, the optical power D and the magnification of the lens Г, we use the formula of a thin lens 1 / F = 1 / d + 1 / f, the definitions of the concepts “optical power of the lens” D = 1 / F and “magnification of the lens” Г = f / d. It is known from the problem statement that the distance from the object to the lens is d = 5 cm = 0.05 m, and from the lens to the image is f = 20 cm = 0.2 m. Substitute the values of the quantities into the calculation formulas:

1 / F = 1 / 0.05 m + 1 / 0.2 m; F = 0.04 m;

D = 1 / 0.04 m; D = 25 diopters;

G = 0.2 m / 0.05 m; G = 4.

Answer: focal length 0.04 m, optical power 25 diopters, lens magnification 4.