Radian and steradian are two fundamental units used in measuring angles and solid angles, respectively, in mathematics and physics. They are essential for understanding and working with various aspects of geometry, trigonometry, and physics. A detailed and clear explanation is given below about radian and steradian. Both **radian and steradian are dimensionless**

## Detailed explanation

**What Is Radian?**

The radian is the standard unit for measuring angles in the International System of Units (SI). It provides a way to express angles based on the** concept of the ratio between the length of an arc and the radius of a circle**. More specifically, a radian is defined as the angle subtended at the centre of a circle by an arc equal in length to the radius of that circle.

In other words, if you take a circle with a radius “r” and measure an arc on the circumference with the same length as “r,” the angle subtended by that arc at the centre of the circle is one radian. Radians are dimensionless, meaning they do not have any associated units. still not clear click here.

**What Is Steradian?**

The steradian is the unit used to measure solid angles in three-dimensional space. It is defined as the **solid angle subtended by a cone with an apex at the centre of a sphere**, where the surface of the sphere cuts an area on the surface of the cone equal to the square of the radius of the sphere.

In simpler terms, it measures the amount of three-dimensional space an object or light source occupies from a particular point of view. The steradian is a dimensionless unit, similar to the radian.

## What is the difference between Radian and Steradian

It is a basic concept in all places. So the difference is given below

**Difference Between Radian And Steradian**

The key difference between radian and steradian lies in the quantities they measure and the dimensions they represent:

Measurement:

Radian (rad): Radians measure angles in a **two-dimensional plane**, specifically the angle subtended by an arc on the circumference of a circle, relative to the center of the circle. Radians are used to express rotational or angular displacement, velocity, and acceleration.

Steradian (sr): Steradians measure solid angles in **three-dimensional space**. They quantify the extent to which an object or light source occupies space from a particular viewpoint.

Dimensions:

Radian: **Radians are dimensionles**s. They do not have any associated units since they represent a pure ratio between the length of an arc and the radius of a circle. Radians are typically expressed as numerical values without any unit.

Steradian: Steradians are also dimensionless. They represent the ratio of the solid angle subtended by a cone to the square of the radius of the sphere. Like radians, steradians are usually expressed as numerical values without any unit.

Note: In summary, a radian is a unit used to measure angles in a two-dimensional plane, **while steradian is a unit used to measure solid angles in three-dimensional space. Radians have no associated units and quantify angular displacement, velocity, and acceleration**. Steradians are also dimensionless and quantify the extent to which an object or light source occupies space from a particular viewpoint.

## Our Opinion

As the definitions and explanations cannot be changed by anyone we provided the information after hard research. This article will be useful for higher studies and competitive exams. This definition will help you to clear your doubts and queries. Apart from exams, it will also help you develop your IQ in many ways. I believe you would gain some information from this article which is unknown.