ANS:B - 0.5-50

The range of 0.5-50 microns indeed represents a broader portion of the electromagnetic spectrum, encompassing both the near-infrared and far-infrared regions. Let's delve into the significance of this range in heat transfer by radiation:

1. Near-Infrared Region (0.7-5 microns):
   • This region includes wavelengths ranging from approximately 0.7 to 5 microns.
   • Near-infrared radiation is important in heat transfer as it carries significant energy and can penetrate surfaces to some extent.
   • It's commonly utilized in various applications such as remote sensing, thermal imaging, and infrared heating systems.
2. Far-Infrared Region (5-50 microns):
   • This region covers wavelengths from approximately 5 to 50 microns.
   • Far-infrared radiation, also known as long-wave infrared radiation, is especially crucial in heat transfer by radiation.
   • This radiation is emitted by all objects with temperatures above absolute zero and is particularly significant for heat exchange between objects at different temperatures.
   • Infrared thermography, used for detecting temperature variations, relies heavily on far-infrared radiation.
   • Many heat transfer calculations, particularly those involving radiative heat exchange between surfaces, focus on this range.