1. Photographic film contains light-sensitive silver halide grains in an emulsion layer that reacts to light exposure. 2. Developing the exposed film in a dark room uses a reducing agent in the developer solution to convert light-struck silver halide grains into metallic silver atoms through a redox reaction. 3. Remaining unexposed silver halide grains are then converted into soluble complexes using a fixer solution so they can be removed, leaving only the black-and-white image formed by the metallic silver.

1. Outline:
1. Photographic film
2. Dark room
3. Redox reaction
4. Half equation

2. - Photographing is based on
Photosensitivity and reaction
with light.
-layers of photographic film:
1. Starch resistant
2. Emulsion layer
3. Adhesive layer
4. Film base
5. Adhesive layer
6. Antihalation layer

3. -emulsion layer is a light sensitive,
formed of silver halide grains in
gelatin layer.
-DARK ROOM:
1. Developer.
2. Stop
3. Fixer
4. water

4. 1. In dark room in developer :
- It contains reducing agents.
-Bromide ion loses an electron
(oxidized) which is gained by silver ion
(reduced) to form a silver atom.
{ latent image which is invisible to eyes
becomes visible}

5. Redox reactions
Ag⁺ Ag
+1 0
1e⁻
Ag⁺+1e⁻ Ag
n=1
Br⁻ Br₂ *2
2 Br Br₂
+2 0
2e⁻
2Br⁻ Br₂+2e⁻
N=2
2Ag⁺+2e⁻ 2 Ag *2
2Br⁻ Br₂+2e⁻
2Ag⁺+2Br⁻ 2Ag + Br₂

6. Redox reactions
2-in dark room fixer solution:
Silver halide is not very soluble in
water .
So the remaining silver halide we
convert it into soluble complex by
reacting it with S2O3⁻