Problem 62 - A Complete Resource Book in Chemistry for JEE Main

Question

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

Step-by-Step Solution

Answer

(a) colloidal silver bromide is used in photography due to its light sensitivity.

Step 1: Understand the Term 'Colloidal Solution'

A colloidal solution, or colloid, is a substance microscopically dispersed evenly throughout another substance. In photography, specific colloidal solutions are used due to their light-sensitive properties.

Step 2: Identify the Use of Colloidal Solutions in Photography

In photography, the colloidal solution used is one that is sensitive to light, which is crucial for capturing images. This light sensitivity is primarily associated with silver halides.

Step 3: Analyze the Options Given

The options provided are: (a) colloidal silver bromide, (b) colloidal gold, (c) colloidal silver, and (d) colloidal sulphur. Among these, silver bromide is known for its light-sensitive characteristics.

Step 4: Determine the Correct Answer

Colloidal silver bromide is widely used in the photographic process due to its sensitivity to light. It represents the emulsions on photographic films and paper that react when exposed to light, creating a latent image.

Key Concepts

Photography

Photography is the art and science of capturing light to create images. Before digital technology, this process relied heavily on chemical principles. Chemical photography uses light-sensitive materials that form images when exposed. Classical photography processes involved film, which had to be developed using photographic chemicals. The exposed film was then processed to reveal the captured image.

Photography relies on the principle of exposing a sensitive material to light. This creates a chemical reaction that captures the scene in detail. The material must be sensitive enough to accurately record various shades and details. This is why specific compounds like silver halides are used, because they can effectively capture light and produce images.

Silver Bromide

Silver bromide is a light-sensitive compound crucial for traditional film photography. It is finely divided in a gelatin medium and coated onto a film or photographic paper.

When you take a photograph, light hits the film and causes a chemical reaction with the silver bromide. This reaction forms a latent image, which is microscopic and invisible at first.

• Once developed, this image becomes visible.
• Silver bromide is highly effective because it reacts well with light, making it ideal for photography.

Silver bromide grains on the film capture the light, distinguishing dark and bright areas. This process allows for high-quality images when properly developed. Naturally, this compound has become synonymous with quality in the realms of traditional photography.

Light Sensitivity

Light sensitivity, or photosensitivity, is the ability of a material to respond to light. In photography, this quality is essential for capturing detailed images.

Silver bromide's efficacy in photography stems from its light sensitivity. It can react to different light intensities and exposures, producing a contrast in images.

• The light-sensitive property allows the film to react appropriately under varied lighting.
• Making it possible to capture clear photos even in different lighting conditions.

This sensitivity dictates the exposure time required for an image; too much or too little can affect image quality. Balancing these factors ensures precision and clarity in every captured image.

Silver Halides

Silver halides are a group of chemical compounds formed by silver and halogens, such as silver bromide, silver chloride, and silver iodide. They are crucial in traditional film photography for their light-sensitive properties.

• When exposed to light, silver halides undergo a chemical change.
• This change forms a latent image that, when developed, reveals the captured photo.

Silver bromide is the most commonly used silver halide in photography due to its superior sensitivity to light. This makes it a preferable choice for creating high-quality photographic prints. While mainly used in traditional photography, their principles still underlay some digital photography techniques.