To give blood you must: 1  Be in general good health.  Be at least 17 years old. (If you are 16 you can donate with a CBC consent form signed by your parent). There is no upper age limit as long as you have no health restrictions.
Specific radiative intensity. Specific (radiative) intensity is a quantity used in physics that describes electromagnetic radiation. It is a term used in much of the older scientific literature. The present-day SI term is spectral radiance, which can be expressed in base SI units as W mâ2 srâ1 Hzâ1.
1 light intensity, also called energy flux or irradiance, which is energy per area per time, typically [W/m2] or [mW/cm2]; or.  photon flux, which is the number of photons per area per time [cmâ2sâ1].