- #1
- 19,865
- 10,860
Definition/Summary
Intensity of radiation = power per area perpendicular to the radiation. It is a vector, parallel to the radiation.
Intensity of radiation = energy density times velocity (therefore sometimes called energy flux).
It is measured in watts per square metre (Wm^{-2})
Equations
For a surface perpendicular to the radiation:
I\ =\ P/area
For a general surface, with normal \hat{\mathbf{n}}:
P\ =\ \int_S \mathbf{I}\cdot\hat{\mathbf{n}}\,dS
Extended explanation
Power per area = energy density times velocity:
Power = energy per time (measured in W\ =\ Js^{-1}).
Power per area = energy per area per time = energy density (ie, per volume) times velocity.
So intensity = power per area = energy density times velocity.
* This entry is from our old Library feature. If you know who wrote it, please let us know so we can attribute a writer. Thanks!
Intensity of radiation = power per area perpendicular to the radiation. It is a vector, parallel to the radiation.
Intensity of radiation = energy density times velocity (therefore sometimes called energy flux).
It is measured in watts per square metre (Wm^{-2})
Equations
For a surface perpendicular to the radiation:
I\ =\ P/area
For a general surface, with normal \hat{\mathbf{n}}:
P\ =\ \int_S \mathbf{I}\cdot\hat{\mathbf{n}}\,dS
Extended explanation
Power per area = energy density times velocity:
Power = energy per time (measured in W\ =\ Js^{-1}).
Power per area = energy per area per time = energy density (ie, per volume) times velocity.
So intensity = power per area = energy density times velocity.
* This entry is from our old Library feature. If you know who wrote it, please let us know so we can attribute a writer. Thanks!