# Convex lens and focal length

• Alche

#### Alche

1)Why when a convex lens having radius of curvature R, focal length f and refractive index μ is

bisected horizontally along the principal axis its focal length remains the same, whereas when

it is bisected vertically focal length becomes 2f? Does the same thing happens in the case of

concave lens too?

Hi Alche! Tell us what you think, and then we'll comment. Tell us what you think, and then we'll comment. Well, I think when we bisect the convex lens vertically its radius of curvature becomes R/2 so the focal length becomes 2f.

And I am sure the same things happens with concave lens too :tongue: Hi Alche! To be honest, I can't remember the formula ,

but yes the vertical cut changes the focal length because it changes the shape of the surface the light refracts through (and so yes, it's the same for a convex lens) …

the horizontal cut doesn't change the shape of the surfaces, it only makes the lens smaller, so the focal length stays the same. Thanks Sir focal length of the lens f = R/2, where R is the radius of curvature of the given lens

## 1. What is a convex lens?

A convex lens is a type of optical lens that is thicker in the middle and thinner at the edges. It is curved on both sides, creating a bulging shape, and is used to converge or focus light rays to a single point.

## 2. How does a convex lens work?

A convex lens works by bending light as it passes through the lens due to the difference in curvature between the center and the edges. This bending of light is known as refraction and it causes the light rays to converge at a point called the focal point.

## 3. What is the focal length of a convex lens?

The focal length of a convex lens is the distance from the center of the lens to the focal point. It is a measure of how strongly the lens converges or diverges light rays. The shorter the focal length, the stronger the lens will converge light.

## 4. How is the focal length of a convex lens determined?

The focal length of a convex lens is determined by its shape and curvature. It also depends on the refractive index of the material the lens is made of. Thicker lenses with a higher curvature will have a shorter focal length, while thinner lenses with a lower curvature will have a longer focal length.

## 5. What are some common uses of convex lenses?

Convex lenses have many practical applications, such as in eyeglasses, cameras, telescopes, and microscopes. They are also used in the production of magnifying glasses, projectors, and laser systems. Convex lenses are also essential in corrective eye surgeries, such as LASIK, to correct vision problems.