Understanding the Difference between Radiance and Irradiance

In summary, radiance and irradiance are two related but distinct concepts used to measure light. Radiance refers to the light leaving a surface, while irradiance measures the light hitting a surface. They are measured in different units and can be affected by factors such as the light source and surface material. The two are related through the inverse-square law and are used in various fields to understand the properties of objects and environments.
  • #1
funcosed
37
0
Radiance, Irradiance?

Homework Statement


Hi, just wondering if my understanding of the difference between these two is correct??


Homework Equations


If radient energy is the energy transported by electromagnetic radiation then radiance is the radient energy crossing a surface per unit time that is traveling normal to the surface.
Irradience is the radient energy crossing the surface from all directions (hemisphere above the surface.


The Attempt at a Solution

 
Physics news on Phys.org
  • #2

FAQ: Understanding the Difference between Radiance and Irradiance

What is the difference between radiance and irradiance?

Radiance refers to the amount of light energy emitted or reflected by a surface, while irradiance is the amount of light energy that falls on a surface. In simpler terms, radiance measures the light leaving a surface, while irradiance measures the light hitting a surface.

How are radiance and irradiance measured?

Radiance is typically measured in watts per square meter per steradian (W/m2/sr), while irradiance is measured in watts per square meter (W/m2). These measurements can be taken using specialized instruments such as radiometers or photometers.

What factors affect radiance and irradiance?

The radiance and irradiance of a surface can be affected by several factors, including the intensity and spectral distribution of the light source, the surface material and its reflective properties, and any intervening media such as air or water.

How do radiance and irradiance relate to each other?

Radiance and irradiance are related through the inverse-square law, which states that the intensity of light decreases proportionally to the square of the distance from the source. This means that as the distance from a light source increases, irradiance decreases faster than radiance.

What applications is radiance and irradiance used for?

Radiance and irradiance are important concepts in fields such as optics, astronomy, and remote sensing. They are used to measure and characterize light from various sources, which can help in understanding the physical properties of objects and environments.

Similar threads

What Are the Differences Between Black Body Radiation Formulas?
Replies
5
Views
808
Radiant Intensity vs. Irradiance
Replies
2
Views
14K
I Relation between spectral radiance and density of cavity
Replies
7
Views
3K
Laser induced damage and irradiation time
Replies
5
Views
1K
What Is the Relationship Between Radiant Intensity and Radiance?
Replies
13
Views
6K
Computing irradiance at a point
Replies
1
Views
2K
Compute temperature rise from solar irradiance
Replies
6
Views
5K
Why is radiance defined per projected area normal to the beam direction?
Replies
4
Views
2K
Radiance of a Lambertian emitter
Replies
7
Views
9K
What are Radiance and Irradiance and how do they differ?
Replies
2
Views
19K

Hot Threads

Recent Insights

Back
Top