______ are also known as heat waves.

Infra-red waves

The correct answer is option 1. Infra-red waves.

Infrared waves, also known as infrared radiation or heat waves, are electromagnetic waves with longer wavelengths than visible light. They are commonly associated with the sensation of warmth and are often used for heating purposes. Infrared waves are emitted by all objects with a temperature above absolute zero and play a significant role in various applications, including thermal imaging, remote sensing, and heating systems.