👉 In mathematics, the concept of Irradiance is a fundamental unit that represents the angle subtended by an arc on a circle or sphere at its center. It can be defined as the ratio of the length of the arc to the radius of the circle or sphere. For example, if we have a circle with a radius of 5 units and an arc length of 10 units (since it is a semicircle), then the angle subtended by this arc at its center would be
