The length of the image is equal to.

Given:

The length of the object is = L, object distance is u and focal length = f. To find the length of the image we use the mirror equation. The Length of the object is

Formula Used:

The mirror formula or mirror equation specifies the relation between the object and image distance to the focal length of the object.

where

u is the object distance, v is the image distance and f is the focal length of the object put in the principal axis.

Explanation:

To find the length of the image that is v, we use

Now separating the size of v with respect to the size of the object and focal length

Due to smaller length of the object () let us differentiate the equation with respect to u and v.

Putting equation (2) in (1) we get

Since

Therefore, the length of the image is equal to