# Quick Answer: Can we find 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). … You can calculate the focal length of the concave lens using the formula f2 = (f1F/(f1-F).

## What is the focal length of a concave lens?

The distance between the pole and the principal focus is called the focal length (f) of the lens. The given focal length of the concave lens is f = -2 m. It is negative because a concave lens always has a negative focal length.

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

i) Place the convex lens on a ‘V’ stand. . ii) Light a candle and take it far away from the lens along the principal axis. iii) Adjust the screen on the other side of the lens to get a clear image on it. iv) Measure the distance between the ‘V’ stand and the screen which gives a rough idea of focal length of the lens.

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

This is the formula for focal length of concave lens which states that the focal length is the product of the image distance and the object distance divided by the difference in the object and the image distance.

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

The focal length of a double convex lens is given by the formula (1/v) + (1/u) = (1/f), where u is the distance between the object and the lens, v is the distance between the image and the lens.

## What is the formula of focal length of concave mirror?

Focal Length of Concave Mirror Formula

The focal length of the convex mirror is positive, whereas that of the concave mirror is negative. The same can also be proved by using the mirror formula: (1/f = 1/v +1/u).

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

Measure the distance between the lens and the wall (screen). This will be equal to the rough focal length of the mirror. Clamp the holder with concave lens on fixed upright on the I side of the convex lens. Fix this upright at some distance away from the convex lens.

## How do you find the focal length of a convex lens experiment?

It can be found by obtaining a sharp image of the Sun or a distant tree on a screen, say a plane wall, or a sheet of paper placed on the other side of the lens and measuring the distance between the lens and the image with a scale. This distance is a rough estimate of the focal length, f of the convex lens.

## Which lens has a negative focal length?

For a convex lens, focal length (f) is positive and for a concave lens, the value of f is negative.

## Why is focal length of concave lens negative?

Light rays from infinity, parallel to the principal axis, thus meet at the a point on the principal axis on the side of the mirror which is towards the object. This distance is considered as negative since it is on the side of the object. Hence the focal length of a concave mirror is negative.

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