Find the distance from the image to the lens if the focal length of the lens is 0.6m

Find the distance from the image to the lens if the focal length of the lens is 0.6m and the distance from the object to the lens is 0.9m?

Let’s write it down briefly:

F = 60 cm;

d = 90 cm;

You need to find:

f -?

To solve the problem, we apply the thin lens formula:

1 / F = 1 / d + 1 / f,

where d is the distance from the lens to the object,

f is the distance from the lens to the image;

F is the focal length of the lens.

Let us express f from the formula:

1 / f = 1 / F – 1 / d;

1 / f = (F – d) / Fd;

f = (F * d) / (F – d).

It remains to substitute the values into the resulting formula and perform calculations:

f = (60 * 90) / (60 – 90) = 5400 / -30 = -180.

f = 180 cm = 1.8 meters.

Answer: f = 1.8 meters.