i) Illumination is directly proportional to the luminous intensity of the source.
ii) Inverse square law – The illumination of a surface receiving its flux from a point source is inversely proportional to the square of the distance between the surface and the source.
iii) Lambert’s cosine law – The illumination of a surface at any point is proportional to the cosine of the angle between the normal at the point and the direction of the luminous flux.

1. The light should not strike directly the eyes.
2. The type and size of the lamp should be correct.
3. Proper location should be made.
4. Reflecting equipment should be suitable for purpose.
5. Hard and long shadows should be avoided.

(a) Nature of the work, (b) Architectual design, (c) Surroundings, (d) nature of light and (e) Maintenance.

The factors are as follows:
i) Illumination level,
ii) Glare,
iii) Shadow,
iv) Space height ratio,
v) Mounting height of the lamp,
vi) Area to be illuminated,
vii) Colour of surrounding walls,
viii) Movement of the object,
ix) Utilization factor and
x) Depreciation factor.

(a) Production factor increases, (b) Accident decreases, (c) Wastage of products decreases.

1. What is light,luminous flux, illumination ?
2. What is direct lighting, semi direct lighting, semi indirect lighting ?
3. What are the laws of illumination ?
4. What are specular reflection and diffuse reflection and glare ?
5. What is an electric lamp and incandescent lamp ?
6. What is a halogen lamp ?
7. What is carbon filament lamp ?
8. What is Carbon arc lamp ?
9. What is a gas discharge lamp ?
10. What is a fluorescent tube ?
11. What is stroboscopic effect ?