Understanding Lighting: Concepts, Production, and Applications
Lighting: An Overview
What is Lighting?
Lighting is the science that studies the major forms of light production, its control, and applications.
What is Light?
Light is a form of energy manifested as electromagnetic radiation perceptible to the human eye.
Key Concepts Related to Light
- Radiation: The transmission of energy through space.
- Wavelength: The distance traveled by a wave in one period.
- Frequency: The number of periods of an electromagnetic wave that occur in one second.
Nature, Production, and Transmission of Light
Nature of Light
White light is not a single entity but a combination of various frequencies spanning the colors of the rainbow.
Production of Light
Light can be produced in several ways, including:
- Pyroluminescence: Light produced by combustion.
- Incandescence: Light produced by heating solids to high temperatures.
- Luminescence: Light produced by electrical discharge in gases or metal vapors.
- LED Technology: Light emitted by a semiconductor diode when an electric current passes through it.
Transmission of Light
Transmission refers to the passage of light through a medium. There are three types:
- Regular Transmission: Light passes through a transparent medium without changing frequency.
- Diffuse Transmission: Light is scattered in multiple directions.
- Mixed Transmission: A combination of regular and diffuse transmission.
Understanding Light Measurement
Luminous Flux
Luminous flux measures the power of visible light emitted by a source.
Efficiency and Luminous Efficacy
Luminous efficacy is the ratio of luminous flux emitted to the electrical power consumed.
Luminous Power
Luminous power is the amount of luminous flux emitted over a specific time and space.
Luminous Intensity
Luminous intensity measures the brightness of a light source in a particular direction.
Illuminance
Illuminance is the amount of luminous flux received per unit area of a surface.
Luminance
Luminance is the brightness of a surface as perceived by the human eye.
Characteristics of Light Sources
Duration or Lamp Life
- Average Life: Time until 50% of lamps in a batch fail.
- Useful Life: Estimated time for optimal performance and cost-effectiveness.
Depreciation of Flow
The decrease in luminous flux over time.
Color Temperature
Indicates the color of light emitted by a source.
Types of Light Sources
Incandescent Lamps
Operation
Based on the emission of visible light due to the heating of a tungsten filament.
Components
- Bulb: Glass enclosure protecting the filament.
- Filament: Thin tungsten wire with high resistance.
- Filament Support: Structure holding the filament in place.
- Filling Gas: Inert gas (argon and nitrogen) to reduce filament evaporation.
- Socket: Connects the lamp to the power supply.
Halogen Lamps
Incandescent lamps containing a halogen gas to improve performance and lifespan.
Discharge Lamps
Operation
Light produced by electrical discharge in a gas-filled tube.
Classification
- Mercury Vapor Lamps: Low and high pressure.
- Sodium Vapor Lamps: High and low pressure.
LED Light Sources
Light emitted by a semiconductor diode.
Lighting Fixtures (Luminaires)
Devices that house and control light sources.
Classification of Luminaires
Degree of Electrical Protection
- Class 0: Functional isolation, no grounding.
- Class I: Functional isolation with grounding.
- Class II: Double insulation, no grounding.
- Class III: Low voltage operation.
Degree of Inflammation of the Mounting Surface
- Suitable for direct mounting on non-combustible surfaces.
- Suitable for direct mounting on combustible surfaces.