transmissivity is the term for materials that do not transmit light.
transmissivity is the term for materials that do not transmit light.
what is the term for materials that do not transmit light?
transmissivity
in the "book of optics", al-haytham claimed the existence of primary and secondary light, with primary light being the stronger or more intense of the two. the book describes how the essential form of light comes from self-luminous bodies and that accidental light comes from objects that obtain and emit light from those self-luminous bodies. according to ibn al-haytham, primary light comes from self-luminous bodies and secondary light is the light that comes from accidental objects. accidental light can only exist if there is a source of primary light. both primary and secondary light travel in straight lines. transparency is a characteristic of a body that can transmit light through them, such as air and water, although no body can completely transmit light or be entirely transparent. opaque objects are those through which light cannot pass through directly, although there are degrees of opaqueness which determine how much light can actually pass through. opaque objects are struck with light and can become luminous bodies themselves which radiate secondary light. light can be refracted by going through partially transparent objects and can also be reflected by striking smooth objects such as mirrors, traveling in straight lines in both cases.
book of optics
black films prevent weed growth, but do not transmit light to heat up the soil; clear films transmit light and heat the soil, but promote weed growth. photosensitive films have been developed that are pigmented to prevent weed growth, but still transmit light to heat the soil. these photosensitive films are more costly than either the clear or black polyethylene sheeting. black plastic mulch controls evaporation from the soil, improves soil water retention. plastic mulching proved to reduce irrigation requirements in pepper by 14-29% because of elimination of soil evaporation.
plasticulture