Electromagnetic Spectrum

Infrared waves are longer than those of visible light, just beyond the red end of the visible spectrum. Infrared falls in the range of the spectrum between microwaves and visible light. It has frequencies from about up to about and wavelengths of about centimeters ( inches) to nanometers ( inches) Infrared light is used in industrial, scientific, and medical applications. Night-vision devices using infrared illumination allow people or animals to be observed without the observer being detected. In astronomy, imaging at infrared wavelengths allows observation of objects obscured by interstellar dust. Infrared imaging cameras are used to detect heat loss in insulated systems, to observe changing blood flow in the skin, and to detect overheating of electrical apparatus. Infrared imaging is used extensively for military and civilian purposes.

Step 1: Understand the relationship between wavelength and radiation type.
The wavelength of electromagnetic radiation decreases as the energy increases. The order of wavelengths from smallest to largest is: -rays, X-rays, ultraviolet rays, microwaves.
Step 2: Conclusion.
The smallest wavelength corresponds to -rays. Final Answer: