# How do you calculate the power of a convex lens?

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The power of a lens is defined as the reciprocal of its focal length in meters, or D = 1/f, where D is the power in diopters and f is the focal length in meters.

## What is the formula of power of convex lens?

Convex lens power is defined as the ability of the lens to converge the rays of light which fall on it as shown in the below figure. It can mathematically be defined as P = 1f, where f is the focal length. S.I. unit of power is the Diopter.

## What is the power of lens in convex lens?

The power of a convex lens (converging lens) is positive as its focal length is positive. The power of a concave lens (diverging lens) is negative as its focal length is negative.

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## What is the power of convex lens of 20cm?

The power of a lens of focal length 20cm is 5D.

## What is the magnification of a convex lens?

Magnification produced by Convex Lens

A convex lens can form virtual as well as real images, so the magnification produced by a convex lens can be either positive or negative. Magnification is positive for virtual image and negative for real image. When |m|>1, the image is magnified.

## How do you find the power of a lens example?

Diopter Formula

Dioptre formula is used to calculate the optical power of a lens or curved mirror. The dioptre is the unit for a measure of the refractive index of a lens. The power of a lens is specified as the inverse of the focal length in meters, or D =[frac{1}{F}], where D is the power in dioptres.

## What is the power of convex lens and concave lens?

Therefore, for a lens, the power of a concave and convex lens is negative and positive respectively. Whereas, for a mirror, the power of concave and convex lens is positive and negative respectively.

## What is the formula of lens formula?

Let’s see how to use lens formula (1/v-1/u= 1/f) to locate images without having to draw ray diagrams.

## What is the power of a convex lens whose focal length is 80cm?

∴ p = 1 80 × 10 2 = 100 80 = 1.25 D .

## How do you find the focal length of a convex lens without calculating?

Explanation: Place the convex lens in such a position that sunlight is perpendicular to the lens. In such a position sunlight would be parallel to the optical axis of the lens. Place a piece of paper behind and parallel to the lens and adjust its distance from the lens so as to obtain a point image of sunlight.

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

To Find Focal Length of Convex Lens

1. The focal length of convex lens is the distance between the centre of a lens and its focus. …
2. The focal length of convex lens formula is object distance multiplied by the image distance divided by the difference of the object distance and the image distance.

## Is the focal length of a convex lens is 20 cm find the power of lens?

For example, if the focal length of a lens is 20cm, that is 0.2m To find the power of this lens, take the reciprocal of 0.2 and we get 5. Therefore the power of this particular lens is 5D.

## What is the power of lens of focal length 10cm?

Hence, the power of the lens is \$10\$ dioptre. Note:The power of a lens is measured in dioptre if and only if the focal length is in meter since diopter is a S.I unit.

## What is the power of convex lens of focal length 10 Centimetre?

When a convex lens of focal length 10 cm is placed in contact with a concave lens, the combination has a power of +5 diopter.