For photographic plates silver halides are used.
i think it means a suspensionof a sensitive silver salt or a mixture of silver halides in a viscous medium (as a Gelatin solution) forming a coating on photographic plates, film, or paper
In the processing of photographic films, plates or papers, the photographic developer (or just developer) is a chemical that makes the latent image Latent_imageonthe film or print visible. It does this by reducing the silver halides that have been exposed to light to elemental silver in the gelatin matrix. As a generalisation, the longer a developer is allowed to work, the greater the degree of reduction of the silver halide crystals to silver and therefore the darker the image.
until celluloid was invented Glass plates were used because it was the only way to suspend the emulsion evenly and allowed light to pass through. It was easier to handle. Some glass plates were large and were put into contact with paper to create a positive image. Chemistry was used to convert the silver halides in the emulsion to visible black metallic silver halides. When light was shone through the glass the black metallic silver halides stopped the light and the paper was exposed where the light pass by the halides. This caused the material being exposed to show a positive image.
There are three basic ingredients in film: silver halides (some combination of silver iodide, silver chloride and silver bromide) to make the film sensitive to light gelatin, to bond the silver halides to the backing material a backing material, which is usually a polyester film but it can be glass. (Cameras on really big telescopes used glass plates because they don't sag in the middle.)
Daguerreotypes were made of copper plates coated with silver. The plates were dipped in an iodine fluid, which created the silver-halide "silver iodide." Silver halides are silver molecules bonded with halogens (elements that end in "-ine"). Silver bromide and silver chloride are also silver-halides. Why make a silver-halide? Because these compounds have a property of photosensitivity (light sensitive). As this coated plates dried, they were exposed to light, hence the reason for the silver compound. Afterwards, they were coated again, this time with mercury heated to 75 degrees Celsius. Finally, they are put in salt water to finish (this part I don't know why it's done...). The final picture was usually put in a glass case to protect it; oils produced by the skin can cause copper to corrode. I hope this information was helpful. If you need more information, feel free to let me know.
X-rays will "Fog" photographic plates. That means the plates act as if 'exposed' to light. If the X-rays are intense enough, the plates will appear to be totally exposed.
daguerreotype is one of the earliest photographic processes, in which the image was produced on iodine-sensitized silver and developed in mercury vapour
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because it was precious
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The fogging of the photographic plates that Becquerel observed in 1896 was caused by the emission of invisible, penetrating radiation from the uranium compound he was studying. This radiation interacted with the photographic plates, causing them to become fogged or exposed. This discovery ultimately led to the further investigation of radioactivity.