## How does radius of curvature affect focal length?

The relation between focal length (f) and radius of curvature (R) of a spherical mirror is that the focal length is equal to half of the radius of curvature i.e. f=R2.

### Is focal length double of radius of curvature?

30 cm. Hint: Generally, if nothing is given about the lens, we take it to be thin and having focal length independent of the refractive index. In that case, we take focal length as half of the radius of curvature.

**Can focal length be greater than radius of curvature?**

Most optical materials have an index of refraction in the range of 1.3 to 1.7 for visible light, so for most lenses, the focal length will be greater than the radius of curvature.

**How focal length of concave mirror will change if its radius of curvature is made double?**

If radius of curvature of a mirror is doubled, its focal length is halved.

## What is the focal length of a double concave lens with a radius of curvature 20 cm?

It is given that the focal length of the lens is 20cm. f=20cm.

### Why is focal length half of radius of curvature?

Proving the focal length is half the radius of curvature: Now the angle between the radius of curvature and principal axis will be equal to the angle at which ray is incident and due to reflections law incident angle would be equal to angle cbf. Hence, in both cases Radius is double the focal length.

**What is the focal length of a double convex lens for which radius of curvature of the surface is 40 cm?**

Thus, the focal length of the given convex lens is 40cm.

**When is the focal length greater than the radius of curvature?**

For the moment, think only about a plano-convex lens, with R2 essentially infinite. Then where n is the refractive index. 2) So, for n < 2, the focal length of a plano-convex thin lens will be greater than the radius of curvature, and for n > 2, the focal length will be less.

## How is the focal length of a lens determined?

Focal length of lenses 2 The focal length of a thin lens depends on the radius of curvature, R,of each surface of the lens, and the index of refraction, n, of the lens material. The lens maker’s equation for the focal length, f, of a lens is1 1 f =(n− 1) 1 R1 + 1 R2 . (1) Because the surface of a lens may be either convex or concave, there are sign

### How is the radius of curvature of a mirror determined?

The radius of curvature (r) is the radius of the lens that forms a complete sphere. Determine the approximate focal length of the given concave mirror by obtaining on the wall the image of a distant tree.

**What is the index of refraction for a diamond lens?**

Most optical materials have an index of refraction in the range of 1.3 to 1.7 for visible light, so for most lenses, the focal length will be greater than the radius of curvature. Diamond, though, has an index of refraction of about 2.4, so such a lens will reverse the usual order.