# What is the focal length of a lens answer?

Define focal length of a lens. Solution : The distance between the optical centre and the focus is known as the focal length.

## What is a focal length GCSE physics?

The distance from the lens to the principal focus is called the focal length .

## How can you define focal length?

Definition of Focal Length It measures the distance, in millimetres, between the optical centre of the lens and the camera’s sensor (or film plane). It is determined with the camera focused to infinity. Lenses are named by their focal length, and you can find this information on the barrel of the lens.

## What is focal length Physics 12?

Focal length of a spherical lens is the distance between optical centre and focus of the lens. The Focal length of a lens is half of its radius of curvature. We usually denote the centre of curvature of a lens with the term 2Finstead of denoting it by C.

## What is focal length in concave mirror?

The distance between the pole of the concave mirror and the focus is known as the focal length of the concave mirror.

## What is the definition of focal point in physics?

focal point. noun. Also called: principal focus, focus the point on the axis of a lens or mirror to which parallel rays of light converge or from which they appear to diverge after refraction or reflection. a central point of attention or interest.

## How do you find the focal length in physics?

The typical focal length formula looks as follows: 1/Focal length = 1/Image distance + 1/Object distance , where: Image distance and Object distance are given in mm.

## What factors determine the focal length of a lens GCSE?

So, focal length depends on the radius of curvature, the refractive index of lens material, and the medium’s refractive index in which the lens is placed.

## What is the difference between focal length and focal distance?

Focal length is the distance from the focusing plane (where the camera’s sensor is) to the rear nodal point of the lens, when focused at infinity. This is a property of the lens, which determines the angle of view as well as the perspective. Focusing distance is the distance from the focusing plane to the subject.

## What is focal plane of a lens?

Definition of focal plane : a plane that is perpendicular to the axis of a lens or mirror and passes through the focus.

## What is called focal length of convex lens?

The distance between the convex lens or a concave mirror and the focal point of a lens or mirror is called the focal length. It is the point where parallel rays of light meet or converge. The focal length varies with the sign (positive or negative) depending upon the nature of the lens and mirror(concave or convex).

## What is focal length Toppr?

It is located at the midpoint of pole and centre of curvature. The distance between the pole and the focus of the mirror is called the focal length of the mirror. Hence, f=2R. Note: Focal length of the mirror is a measure of power of the mirror.

## What is focal length and centre of curvature?

Finally, the distance from the mirror to the focal point is known as the focal length (represented by f). Since the focal point is the midpoint of the line segment adjoining the vertex and the center of curvature, the focal length would be one-half the radius of curvature.

## What is focal length and power of plane mirror?

Hence, the focal length of the plane mirror is also infinity. Now, power $\textP = \dfrac1\infty = 0$. Hence, the power of the plane mirror is zero.

## What is focal length of convex mirror?

So, f=2R or focal length of a convex mirror is half of its radius of curvature.

## Why is focal length of convex mirror positive?

(a) A convex mirror has a positive focal length because the focus of a convex mirror is on the right side and behind the mirror. (b) A concave mirror has a negative focal length because the focus of a concave mirror is on the left side and in front of the mirror.

## What is mean by focal length of a convex mirror?

The definition of focal length can be stated as the length between a lens of a convex type or a mirror of concave type and the point of focus of the lens or the mirror is known as the focal length. A focal length is a point where the meeting or converging of the parallel rays of the light takes place.

## Why is focal length important in physics?

A positive focal length indicates that a system converges light, while a negative focal length indicates that the system diverges light. A system with a shorter focal length bends the rays more sharply, bringing them to a focus in a shorter distance or diverging them more quickly.

## What is focal length and principal focus?

Principle focus : The principal focus of a convex lens is a point on its principal axis to which light rays parallel to the principal axis converge after passing through the lens. Focal length: The distance of the principle focus from the optical center of a lens is called its focal length .

## What is focal length in physics class 10?

The distance between the focus and the optical center is known as focal length. It is denoted by f. Focal length is equal to half the radius of the curvature i.e. f=r/2.

## Is focal length the same as image distance?

The image distance is the distance from the thin lens to the image. The focal length is a characteristic of the thin lens, and it specifics the distance at which parallel rays come to a focus.

## How do you find the focal length of a concave lens?

You can calculate the focal length (F) of combination of lenses using the formula F = uv/(u+v). The focal length of convex lens (f1) is shown inside the simulator window. You can calculate the focal length of the concave lens using the formula f2 = (f1F/(f1-F).

## What is focal length in relation to converging lenses?

The distance from the lens to the focal point is called the focal length. For converging lenses, the focal length is always positive, while diverging lenses always have negative focal lengths.

## Why is the focal length of a concave lens negative?

That means that the focal point is on the same side of the lens as the light rays were coming from. Convex lenses have real focus while concave lenses have virtual focus hence the focal length is positive and negative for convex and concave lenses respectively. ∴ The power of the concave lens is negative.

## What is the focal length of a concave mirror and convex mirror?

According to cartesian system focal length of a concave mirror is negative whereas radius of curvature of convex mirror is positive.