# Can you measure approximate focal length of concave lens?

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You can calculate the focal length (F) of combination of lenses using the formula F = uv/(u+v). The focal length of convex lens (f1) is shown inside the simulator window. You can calculate the focal length of the concave lens using the formula f2 = (f1F/(f1-F).

## How do you find the approximate focal length of a concave lens?

To determine focal length of a given concave mirror

To obtain a clear, sharp image the screen should be adjusted. Using a metre scale the distance between the concave mirror and screen can be determined. The distance is the same as the focal length of the given concave mirror.

## How can you measure the approximate focal length of a concave mirror?

Measure the distance between the concave mirror and the screen with given metre scale. This measured distance is focal length of concave mirror.

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## How do you find approximate focal length?

By moving the convex lens to and fro along the scale, focus a distant object on the wall. The image which forms on the wall is very near to the focus of the lens and the distance of the lens from the image is read directly by the metre scale. This gives the approximate focal length of the lens.

## Can you measure the rough focal length of a concave lens?

(b) No, because a concave lens forms a virtual image that cannot be taken on a screen.

## What is approximate focal length of the lens?

By moving the convex lens to and fro along the length of the metre rule, focus the object on wall. The image formed on the wall is almost at the focus of the lens and from the image, the distance of the lens is read directly by the metre scale. This gives the approximate focal length of the lens.

## How is the approximate focal length of a convex lens found can this method be used for a concave lens justify?

Is the same method applicable to a concave lens? The rough focal length of a convex lens is obtained by forming sharp image of a very distant object on a screen. … This method is not applicable to a concave lens, as image formed by a concave lens is virtual and it can be taken on a screen.

## How do you find the focal length of a concave lens Class 10?

Place the screen in front of the reflecting surface of the mirror. Move the screen back and forth until a clear, sharp image of the distant object is obtained on the screen. Measure the distance between the concave mirror and the screen with a metre scale. This distance is the focal length of the given concave mirror.

## How do you find the focal length given the magnification and object distance?

If you know the distance of the object you’re magnifying from the lens and the focal length of the lens, finding the distance of the image is easy with the lens equation. The lens equation is 1/f = 1/do + 1/di, where f = the focal length of the lens.

## What factors determine the focal length of a lens?

So, focal length depends on the radius of curvature, the refractive index of lens material, and the medium’s refractive index in which the lens is placed. Note: Focal length is the length between the middle of the lens and the principal foci.

## How do you find the focal length of a concave mirror in the lab class 9?

Measure the distance between the concave mirror and the screen with given metre scale. This measured distance is focal length of concave mirror. Repeat the process two or three times. Take the mean of the measured focal length.