Question

Which of the following colloidal solution is used in photography? (a) colloidal silver bromide (b) colloidal gold (c) colloidal silver (d) colloidal sulphur

Short answer

Colloidal silver bromide (a) is used in photography.

Step-by-step solution

Identifying the Context of Photography

Photography involves capturing images on a photosensitive surface, typically using materials that can react to light to create images. The common materials used in traditional black and white photography involve a process that uses light-sensitive compounds.

Understanding Colloids

A colloid is a solution where tiny particles are evenly dispersed within a continuous medium without settling to the bottom or forming sediment. In the context of photography, colloids can play a role in how light interacts with the materials used.

Evaluating Each Option

(a) Colloidal silver bromide is a key ingredient in photographic emulsions used in film photography due to its sensitivity to light. (b) Colloidal gold is used in medical and scientific applications, not photography. (c) Colloidal silver has antimicrobial properties and is not used in photography. (d) Colloidal sulphur is used in medical and agricultural settings.

Selecting the Correct Answer

Given the application in traditional photography, colloidal silver bromide is used due to its ability to react to light and form images. Hence, option (a) is the correct choice.

Key concepts

Photographic Emulsions

In traditional film photography, photographic emulsions play a crucial role. These emulsions consist of a suspension of fine particles, often silver halides, in a gelatin binder. Photographic emulsion is applied to a base, usually a flexible plastic film or a glass plate, which provides a surface for capturing images.

Photographic emulsions are light-sensitive. This means they can react to light exposure, changing chemically when exposed to certain wavelengths of light. This characteristic is essential because it allows for the capture of images. When light hits these sensitive compounds, the emulsion undergoes a series of chemical reactions.

• The sensitivity of the silver halides to light is what allows for the formation of a latent image, an invisible image that becomes visible upon developing.
• After exposure, the film is processed to turn the latent image into a visible one through a series of chemical treatments. This involves developing, stopping, and fixing processes.
• Emulsions can vary not just in their sensitivity to different wavelengths but also in their granularity and contrast characteristics.

Regardless of these variations, the fundamental principle remains the same: converting light into an image-bearing medium.

Light-sensitive Compounds

Light-sensitive compounds are essential for producing images in traditional photography. These special substances, mostly made up of silver halides like silver bromide, are sensitive to light exposure. They are a key part of the coating found in photographic emulsions on film or plates.

When these light-sensitive compounds are exposed to light, they undergo a chemical change. This change is the foundation of image creation in photography. Here’s a breakdown of how light-sensitive compounds work in this context:

• Initial Exposure: The exposure to light causes silver ions in the silver halide to become metallic silver, forming a latent image. This image is not yet visible and requires further processing to appear.
• Developing: During the developing process, the latent image is amplified. The areas exposed to light increase their metallic silver content, becoming darker upon development.
• Fixing: This step involves washing away unexposed silver halide, stabilizing the image and making it insensitive to further exposure to light.

These processes enable the transfer of a real-world scene onto a tangible medium.

Traditional Film Photography

Traditional film photography refers to the process of capturing images using a film coated with photographic emulsion. Unlike modern digital photography, which captures images electronically, traditional photography relies on chemical reactions.

The workflow of traditional photography can be broken down into a few key steps:

• Exposure: Light from a scene enters through the camera lens and hits the film. The light exposure creates a latent image in the light-sensitive compounds of the film’s emulsion.
• Developing: This involves immersing the film in a series of chemical baths to convert the latent image into a visible one. This step determines the contrast and detail in the final photograph.
• Fixing: After developing, the film undergoes fixing to remove any unexposed silver halide. This ensures the image remains unchanged when exposed to light during subsequent viewing.

Traditional film photography is lauded for its detail and artistic quality, offering a unique depth and character not easily replicated by digital methods. Despite its decline in popularity with the advent of digital photography, many enthusiasts continue to appreciate the craftsmanship of traditional methods.