# Question: What happens to the focal length of a converging lens when it is placed under water?

## What happens to the focal length of lens when it is immersed in water?

focal length depends upon refractive index of lens with respect to medium. hence, after immersing of lens in water focal length of lens increases.

## Will the focal length of a lens change when it is submerged in water?

Yes, focal length of lens changes when submerged in water. It is because lens worked on refraction phenomenon. Angle of refraction depends on the index of refraction medium from which light incident.

## What happens to the focal length of a lens when dipped in water of refractive index 4 3?

Answer: The focal length of the lens in water is reduced to two by third of focal length of the lens in air. We know that, The focal length of the lens is inversely proportional to the refractive index. When the refractive index will be decreases then the focal length will be increases.

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## When a converging lens is immersed in water does its focal length increase or decrease in comparison with the value in air explain?

When immersed in water, the difference between light’s speed in the lens and the surrounding medium is less than the difference when it’s in air, and the focal length of a lens would be greater under water.

## What will be the Behaviour of a lens if it is placed in water instead of air?

Focal length depends upon the refractive index of the material of the lens with respect to the medium surrounding it. Since the surrounding medium changes from air to water, the refractive index decreases and so the focal length of the lens increases.

## What happens when focal length increases?

Lenses with short focal lengths will have a wide angle of view, while longer focal length lenses will have stronger magnification, creating what is called a telephoto lens. As the focal length value decreases, the lens becomes a wide-angle lens, and as the value increases it becomes a telephoto lens.

## What does focal length depend on?

The principal focal length of a lens is determined by the index of refraction of the glass, the radii of curvature of the surfaces, and the medium in which the lens resides. It can be calculated from the lens-maker’s formula for thin lenses.

## How is focal length related to refractive index?

Since from lens makers formula we can observe that focal length of lens is inversely proportional to refractive index of medium of lens. Hence net refractive index of lens decreases when it is dipped in a denser medium than air, hence focal length increases.

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## Does focal length of lens change?

The focal length of the lens varies directly with the wavelength of the light used and as wavelength is inversely related to refractive index, the focal length also varies inversely with it. The frequency of light has no effect on the focal length.

## When a lens is dipped in water?

When a convex lens is dipped in water its focal length changes and relative refractive index changes which makes it less converging.

## What happens when a lens is dipped in water?

When a convex lens is dipped in water its focal length changes and relative refractive index changes which makes it less converging.

## What happens to focal length of convex lens when it is cut horizontally?

Answer. If a convex lens is cut horizontally then radii of curvature on both sides of the lens i.e., R1 and R2 will remain same as before. As R1 and R2 do not change, so there will be no change in focal length of the lens. Although the intensity of the image will reduce.

## What type of lens is converging?

A double convex lens is a converging lens. A double concave lens is also symmetrical across both its horizontal and vertical axis. The two faces of a double concave lens can be thought of as originally being part of a sphere.

## What is the focal length of a plane mirror?

The focal length of a plane mirror is infinity as the image can be formed at an infinite distance inside the mirror. A plane mirror can be recognised as a spherical mirror of infinite radius of curvature. Focal length is half of the radius of curvature and hence it is infinity.

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## Which lens thick or thin has greater focal length?

Thick lens will have shorter and consequently thin lens will have greater focal length. Because, For a thick lens, the optical path length of the light is more, than for a thin lens, thus, the bending of light will be more in case of a thicker lens. Consequently, it has a shorter focal length.