Teacher please Answer me 7th
Dear student,
The approximate focal length of a convex lens can be measured by a method called distance object method. The principle of this method is that a beam of parallel rays coming from a distant object get converged by a convex lens in the focal plane of it.
For example, in an open space, against a white paper (placed on a vertical wall), one meter scale is placed horizontally .Now hold a lens vertically on the scale and try to focus a distant object, let us say a tree. The object will be focused as we move the lens to and fro along the length of the scale. As the light rays coming from a distant object is considered to be parallel only, the image of it will be formed on the white paper at the focus of the lens. And we can easily read out the distance of the lens from the paper on the meter scale. This gives the value of approximate focal length of the convex lens.
Regards,
The approximate focal length of a convex lens can be measured by a method called distance object method. The principle of this method is that a beam of parallel rays coming from a distant object get converged by a convex lens in the focal plane of it.
For example, in an open space, against a white paper (placed on a vertical wall), one meter scale is placed horizontally .Now hold a lens vertically on the scale and try to focus a distant object, let us say a tree. The object will be focused as we move the lens to and fro along the length of the scale. As the light rays coming from a distant object is considered to be parallel only, the image of it will be formed on the white paper at the focus of the lens. And we can easily read out the distance of the lens from the paper on the meter scale. This gives the value of approximate focal length of the convex lens.
Regards,