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.
Intensity is power per unit area. Power is energy per time. For a photon, the energy is $h\nu$. So, the intensity will be $$I=Nh\nu / A$$ if $N$ is the monochromatic photon emission rate (photons per second), $\nu$ is the frequency of the photons, and $A$ is the area these photons are hitting.