A lens with a focal length of 2m gives an image of an object on the screen, magnified 4 times.

A lens with a focal length of 2m gives an image of an object on the screen, magnified 4 times. what is the distance from the subject to the lens.

The focal length of a lens can be calculated using the formula:
1 / F = 1 / d + 1 / f, where F is the focal length of the lens (F = 2 m), d is the distance from the object to the lens (m), f is the distance from the lens to the image (m).
Lens magnification:
Г = f / d, where Г – lens magnification (Г = 4).
f = G * d.
Let’s express and calculate the distance from the object to the lens:
1 / F = 1 / d + 1 / (G * d) = (G + 1) / (G * d).
f = (G + 1) * F / G = (4 + 1) * 2/4 = 5 * 2/4 = 2.5 m.
Answer: The distance from the object to the lens is 2.5 m.