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The focal length of a concave surface is negative, whereas the focal length of a convex surface is positive. Therefore, for a lens, the power of a concave and convex lens is negative and positive respectively.

## What is power of concave lens?

The power of the concave lens is negative. Concave lens surfaces have a virtual radius of curvature, and thus a negative curvature. Optical power is denoted by the same convention signs that are used for focal length.

## What is the power of the convex lens?

The power of convex lens is positive.

## How do you find the power of a concave and convex lens?

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.

## Is power of convex lens positive?

The power of a lens is defined as the reciprocal of the focal length. … Converging (convex ) lenses have positive focal lengths, so they also have positive power values. Diverging (concave ) lenses have negative focal lengths, so they also have negative power values.

## Which is convex lens?

A convex lens is also known as a converging lens. A converging lens is a lens that converges rays of light that are traveling parallel to its principal axis. They can be identified by their shape which is relatively thick across the middle and thin at the upper and lower edges.

## 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.

## Which lens has power in negative?

Concave lens has negative power as its focal length is negative.

## What is power of lens Class 10?

Power of a lens is the ability to converge or diverge the ray of light falling on it. Power of a lens is defined as reciprocal of focal length of the lens.

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

Answer

- Given that, Focal length of the concave lens, f = 2 m.
- To find, Power of the lens.
- Solution, The relation between power and focal length of the lens is inverse. Power is given by : P = 1/f.
- f is the focal length of the lens and it is negative for concave lens.

## What is power of concave lens of focal length 2m?

Detailed Solution

The focal length of the concave lens is always negative. Hence, the given focal length is -2m. Formula: Power = 1/focal length. Hence, Power is -0.5 dioptre.

## Which lens has a positive power?

(a) Convex lens has positive power.

## Why is the power of a concave lens negative?

The power of the lens is the reciprocal of the focal length. A concave lens is a diverging lens, so it will always have a negative focal length. Therefore, the power of a concave lens is also negative.

## When power of lens is positive or negative?

Power of a lens is inverse of its focal length. The focal length of convex lens is positive, so its power is also positive. The focal length of concave lens is negative, so its power is also negative.