Transmission vs. Transmittance — What's the Difference?

Transmission involves the act of conveying or transferring something from one place, person, or thing to another. It can apply to various contexts, including the spread of diseases, the transfer of energy, or the sending of data over a distance. Transmittance, however, specifically quantifies how much light or electromagnetic radiation is allowed to pass through a material, with the remainder being absorbed or reflected.

In physics and engineering, transmission is a broad concept that encompasses the movement of electromagnetic waves, particles, or information. It is not limited to light and can include other forms of energy, such as sound or electrical power. Transmittance is a more specific term, used primarily in optics and materials science to describe how transparent a material is to light or specific wavelengths of electromagnetic radiation.

Transmission efficiency can vary greatly depending on the medium and the energy form being transmitted. For example, electrical transmission lines can lose energy due to resistance and heat. Transmittance, on the other hand, is specifically concerned with the efficiency of light passing through a material and is calculated as the ratio of transmitted light to incident light, often affected by the material's thickness, composition, and the wavelength of the light.

While transmission can apply to both tangible and intangible entities (like power or information), transmittance is used to describe a physical property of materials that affects how light interacts with them. This makes transmittance an important factor in designing optical systems, choosing materials for lenses, filters, and windows, and understanding the behavior of light in different environments.

Both transmission and transmittance play critical roles in various technological and scientific fields, but they are applied differently. Transmission is crucial for communication systems, power distribution, and mechanical systems. Transmittance is key in optics, photonics, and materials science, influencing the development of products and technologies that rely on the control of light.