普朗克定律(Planck's distribution law)描述的是( )
A.
黑体发射力 (Total, hemispherical blackbody emissive power)
B.
黑体光谱半球发射力 (Spectral, hemispherical blackbody emissive power)
C.
黑体光谱定向发射力 (Spectral, hemispherical blackbody emissive power)
D.
光谱辐射强度 (Spectral Intensity of the emitted radiation)