# What magnification can be obtained with a precision flashlight

**What magnification can be obtained with a precision flashlight, the lens of which has a main focal length of 40 cm if the distance from the lens to the screen is 10m**

To determine what magnification Г can be obtained with a projection light, we use the definition of this concept: Г = f / d, where d is the distance from the object to the lens, f is the distance from the lens to the image. The distance d is found from the thin lens formula 1 / F = 1 / d + 1 / f, we get: d = F f / (f – F). Then:

Г = f · (f – F) / (F · f) or Г = (f – F) / F.

It is known from the problem statement that the lens of the projection lamp has the main focal length F = 40 cm = 0.4 m, the distance from the lens to the screen f = 10 m. Substitute the values of the quantities into the calculation formula:

G = (10 m – 0.4 m) / 0.4 m;

G = 24.

Answer: With a projection light, you can get a magnification of 24.