The electromagnetic waves with wavelengths ranging from the size of a printed period to lengths of 10⁻³ to 10⁻¹ meters are infrared radiation.

Here's why:

* Infrared radiation falls within the electromagnetic spectrum between visible light and microwaves. Its wavelengths are typically measured in micrometers (µm), which range from about 700 nm (near-infrared) to 1 mm (far-infrared).

* A printed period is roughly 0.5 mm in size, which fits within the far-infrared range.

* Lengths of 10⁻³ to 10⁻¹ meters (or 1 mm to 10 cm) also fall within the infrared spectrum, particularly the far-infrared region.

Let me know if you have more questions!