Explanation:

Transmissivity refers to the ability of a material to transmit or allow the passage of radiation through it. It is a measure of the fraction of incident radiation that is transmitted through the material. In the context of incident radiation, transmissivity can vary with different factors.

Wavelength:
The wavelength of incident radiation can have a significant effect on transmissivity. Different materials have different transmissivity characteristics for different wavelengths of radiation. This is because the interaction between radiation and the material depends on the energy of the radiation, which is related to its wavelength. Some materials may be transparent or have high transmissivity for certain wavelengths, while being opaque or having low transmissivity for others. For example, glass is transparent to visible light but opaque to ultraviolet (UV) radiation.

Surface Area:
The surface area of the material through which radiation is incident can also affect transmissivity. This is because the surface area determines the amount of radiation that can interact with the material. Generally, larger surface areas allow for more radiation to interact with the material, increasing the chances of transmission. However, it is important to note that the transmissivity may also depend on the angle of incidence and the surface properties of the material, such as reflectivity and scattering.

Time:
The time of exposure to incident radiation can also influence transmissivity. This is particularly relevant in cases where the material may undergo changes over time due to exposure to radiation. For example, some materials may become discolored or degraded when exposed to certain types of radiation for extended periods. These changes can affect the transmissivity of the material, altering its ability to transmit radiation.

Temperature:
Temperature can also have an impact on transmissivity. This is because the physical properties of materials, including transmissivity, can be temperature-dependent. For example, some materials may exhibit changes in transmissivity as their temperature increases or decreases. This can be attributed to changes in the material's molecular structure or other physical properties that occur with temperature variations.

In summary, while all the factors mentioned (time, temperature, surface area, and wavelength) can potentially influence the transmissivity of a material to some extent, the wavelength of the incident radiation is the most significant factor determining transmissivity. Different materials have different transmissivity characteristics for different wavelengths of radiation.