What is light?
Light, electromagnetic radiation that can be detected by the human eye. There are many sources of light. A body at a given temperature emits a characteristic spectrum of black-body radiation. A simple thermal source is sunlight , the radiation emitted by the Chromosphere of the Sun at around 6,000 kelvins (5,730 degrees Celsius; 10,340 degrees Fahrenheit) peaks in the visible region of the electromagnetic spectrum when plotted in wavelength units and roughly 44% of sunlight energy that reaches the ground is visible.Another example is incandescent light bulbs, which emit only around 10% of their energy as visible light and the remainder as infrared. A common thermal light source in history is the glowing solid particles in flames, but these also emit most of their radiation in the infrared, and only a fraction in the visible spectrum.
Day lighting
As the Sun crosses the sky, it may appear to be red, orange, yellow or white depending on its position. The changing color of the Sun over the course of the day is mainly a result of scattering of light and is not due to changes in black-body radiation. The blue color of the sky is caused by Rayleigh scattering of the sunlight from the atmosphere, which tends to scatter blue light more than red light..For colors based on black-body theory, blue occurs at higher temperatures, while red occurs at lower, cooler, temperatures. This is the opposite of the cultural associations attributed to colors, in which red represents hot, and blue cold.
History of Lighting
In the beginning, there was light. Everyone knows that part. But how did we learn to control and use it for ourselves? This history highlights several technologies that have been used to produce light: flame from wood, oil and gas; arc or glow from electricity; and the fluorescence of minerals.
Sun
65 million years BC Fire
450 BC Oil Lamp (Egypt)
1808 AD Carbon Arc Lamp(Davy)
1879 AD Incandescent Lamp (Edison)
1906 AD High Pressure Mercury Discharge Lamp
1910 AD Drawn Tungsten Filament Lamp
1923 AD Low Pressure Sodium Vapor Lamp
1924 AD Gas Filled Incandescent Lamp
1933 AD Fluorescent Discharge Lamp
1958 AD Laser Beam Light Source
Carbon-Arc Lamp:-
Jablochk off electric arc light. Carbons are side-by-side, separated by plaster. Usually, more than one “candle” was placed inside a diffusing globe to reduce the glare of the arc and distribute the light uniformly.
Kerosene lamps:-
Kerosene lamps of the 19th century. They all used the kerosene burner developed by Michael Dietz in 1868. The “Dietz burner” became a worldwide standard.
Electric incandescent lighting:-
The first commercial incandescent lamps of Joseph Swan (left) and Thomas Edition (right). Swan’s lamp used a cellulose filament and spring-clip mechanism to hold the lamp and deliver electric power. Edison’s used a bamboo filament and a screw base. Edison’s base became a worldwide standard.
Coal gas system:-
Early coal gas system. The gas generator is on the right, showing the retort holding coal and the fire used to heat it. The water scrubber in the middle shows gas being bubbled through water to remove impurities. The storage tank on the left has an inverted cylinder counter-balanced over water. This arrangement provided a more-or-less constant gas pressure at the outlet. On top of the tank are typical, very early gas burners.
Sodium discharge lighting:-
Engineers George Inman and Richard Thayer lead the team at General Electric in Cleveland, Ohio, to develop the fluorescent lamp.
Architectural lighting design:-
It is a field within architecture, interior design and electrical engineering that is concerned with the design of lighting systems, including natural light, electric light, or both, to serve human needs.
The design process takes account of:
- The kind of human activity for which lighting is to be provided
- The amount of light required
- The color of the light as it may affect the views of particular objects and the environment as a whole
- The distribution of light within the space to be lighted, whether indoor or outdoor
- The effect of the lightened system itself on the user
Importance of Lighting in Interior Design
The lighting in a home changes the mood of a room just as it does the perceived size of a room. Placement and type are important aspects of interior design, and they work in conjunction with color selections, room size, availability of natural light and furniture selection. The elements that come together when the right lighting is achieved transform a room into a seamless combination of functionality and style.
Color Management
The use of lighting can add to or subtract from the overall colors of a room or from only those surfaces the light is meant to enhance. Darker colors make a room feel smaller and cramped, while light-colored walls do the opposite. The illusion of space is defined by light reflected off of the surfaces of the walls. Some types of lighting help with this illusion by further illuminating the walls. In addition, directional lighting, such as a track light, can soften the wall colors. There is also recessed can lighting, which has a soft, downward glow that illuminates the floors, not walls. This is opposed to lights hung from the center of the room, which provide ambient illumination, or wall lighting. In both cases, this can affect how light or dark a colored section can appear.
Directional Lighting
The lighting in a room either provides illumination for the entirety of the room, or it highlights very specific elements. Track lighting is the perfect example of positional lighting. Hung from the ceiling, the adjustable necks and lamps can be pointed at specific elements, such as a wall painting, the vase of flowers on an entryway table or the bar top or kitchen island. Consider mounting them on the walls, also. Special picture and mirror frames also have built-in lighting to highlight specific areas on a wall. Recessed lighting can be used in floors and ceilings to create vertical beams of light as opposed to an overall glow from central light fixtures hanging from a ceiling.
Functionality
One major role of lighting in the interior setting is functionality. Lighting needs to serve a purpose, or it simply wastes electricity. Chandeliers are not only used in large, open foyers, entryways and rooms because of their centrally themed placement but also because they provide excellent illumination for the room. Wall lights add length and size, visually, to an entryway hall, as well as light the way. Consider the style of lighting you want to ensure you get the best directional or luminescent type for the setting. Look into task-specific lighting for desks and other work areas where functionality is more important than overall room illumination.
Space
Both natural and man-made lighting help with the illusion of space. For a darker room, find ways to bring in more full-spectrum natural light. If the room does not have sufficient lighting, it will feel cramped. This is worsened by close-proximity furniture arrangements, such as coffee table, end table, sofa, chair and love seat combinations in a smaller setting. Corner lamps, wall sconces and centrally hanging lights on the ceiling help brighten a room if natural lighting is not available and help create a visually larger space. This applies to any setting — home or office. Natural lighting is preferred above man-made lighting because it shows off colors better and adds to the visual space of a room by bouncing off reflective surfaces. Consider skylights or large windows if you want more natural light, or use sheer drapes and curtains to allow the maximum amount of light from your current windows.