Types Of Light And Their Importance In Human Life

Light

Johann Ritter is best known for his discovery of ultraviolet light in 1801. A year earlier, in 1800, William Hershel discovered light. This was the first time that a form of light beyond visible light had been detected. The first practical electric light which was the carbon arc was invented by Humphry Davy around 1805. It was used commercially beginning in the 1870s for large building and street lighting until it was superseded in the early 20th by the incandescent light. Light is a source of illumination, whether a natural one (sun) of man-made one (lamp). Light can be explained as a form of electromagnetic radiation with a wavelength and can be detected by human eye. It is a small part of electromagnetic spectrum and radiation given off by stars and sun. Beside human, animals can see light too. In physics, light is a term that sometimes refer to electromagnetic radiation of any wavelength, whether visible or not. The human eye sees each wavelength as a different colour. Rainbows show the entire spectrum of visible light. Light can be said composed of particles called photons. Most of these photons are produced when the atoms in an object heat up. Heat “excites” the electrons inside the atoms and they gain extra energy which is then released as a photon. The hotter an object gets, the more photons it gives out. Light produces when a photon is created when an atom absorbs energy. This energy then increases the potential of one of the electrons in the atom, and then the electron drops back to its normal energy level. The Sun is the dominant source for visible-light waves our eyes receive. The outer-most layer of the Sun’s atmosphere, the corona, can be seen in visible light. But, light can be created when an electron moves from higher to lower energy level. This light is converted to visible light through fluorescence. An incandescent bulb creates light by making a hot filament. Light has kinetic energy. This is the energy of the light due to its motion. This is because photon has no mass, its kinetic energy equals its total energy. The energy of light allows it to create a gravitational field according to General Relativity.

Lighting

Use of an artificial source of light for illumination. Residential lighting uses mainly either incandescent lamps or fluorescent lamps and often depends heavily on moveable fixtures plugged into outlets; built-in lighting is typically found in kitchens, bathrooms and corridors and in the form of hanging pendants in dining rooms and sometimes recessed fixtures in living rooms. Lighting in non-residential buildings is predominantly fluorescent. High-pressure sodium-vapour lamps (electric discharge lamp) have higher efficiency and are used in industrial applications. Halogen lamps have residential, industrial and photographic applications. Depending on their fixtures, lamps produce a variety of lighting conditions. Lighting help you to perform tasks more easily, makes you feel safer and comfortable. Lighting also adds beauty and drama to a room. It can make a small room open and airy, and a large room appear cozy and inviting. When planning your lighting, look at the activities that occur in each room, the atmosphere you want to create and the decorative elements you wish to emphasize. Light can be absorbed and even wasted in dark-coloured room, reflected and used as additional illumination in light-colored room. There are three basic types of lighting that work together to light a building; general, task and accent. A goof lighting plan combines all three types to light an area, according to function and style.

General Lighting

Provides an area with overall illumination. Also known as ambient lighting, general lighting radiates a comfortable level of brightness, enabling one to see and walk about safely. It can be accomplished with chandeliers, ceiling or wall-mounted fixture, recessed or track lights and with lanterns outside your home. A basic form of lighting that replace sunlight, general lighting is fundamental to a lighting plan.

Task Lighting

Helps to perform specific tasks such as reading, sewing, cooking, homework, hobbies, games or balancing your check book. It can be provided by under cabinet, tape and track lighting, pendant lighting and portable lamps. Task lighting should be free of distracting glare and shadows and should be bright enough to prevent eyestrain.

Accent Lighting

Add drama to a room by creating visual interest. As part of a decorating scheme, it is used to spotlight paintings, houseplants, sculpture and other prized possesions or to highlight the texture of a wall, drapery or outdoor landscaping. Accent lighting requires at least three times as much light on the focal point as the general lighting around it. This usually provided by track, under cabinet, tape, or wall-mounted fixtures.

Natural Light

Natural light is the light generated naturally. The most common source of natural light on Earth is the Sun. we receive natural light throughout our sunlight hours, weather we love it or not. It creates the ambient natural light. Sunlight and the atmosphere create the colour and light intensity. It is create by a range of different wavelengths of light radiating from the part of the electromagnetic (EM) spectrum to which the human eye is sensitive. The visible wavelengths only include light that we can see. This light is good for our health. Natural light may also refer to; daylight, sunlight, moonlight and fire. There are even some animals and plants that can create their own light, such as fireflies, jellyfish and mushroom. This is called bioluminescence. Experts estimate that 47% of the energy used in home is for space conditioning (lighting and temperature control). Natural; light produces energy savings by allowing a homeowner, in certain cases, to use less heat, less air conditioning and eliminates the need to use artificial light. The use of natural; light in a home or business space is cleaner for all inhabitants and also help preserve the environment. Aside from health and energy saving benefits, natural light is also helpful for increasing the aesthetic of a space. Architects use natural light to make spaces appear larger, illuminate an interior structure and increase the beauty of a space. Natural light also can play an important role in creating a comfortable environment, helping to regulate the body clock, improve concentration and create a calm and tranquil setting. It can reduce the energy consumption of a building compared to artificial light and can also help prevent mould or mildew from developing in buildings sin ce these spores thrive in darkness. Typically natural light is transmitted to the interior of a building through glazing such as windows or through other opening.

Man-made light

Artificial light is light created by humans. There are many examples of man-made light such as candles, matchsticks and flashlights. It needs to be generated with energy and you can turn it off and on like a switch. The visible part of the spectrum includes the colours of light which you can see with your own eyes. Three sources of man-made lights are fluorescent lights, incandescent lights and light from LED’s. Man-made light is used in various ways. Human have created this type of light and many people use it everyday. A light bulb is a type of an artificial light. It lasts a long time, but then sun lasts way longer. The electric light, one of the everyday conveniences that most affects our lives, was not “invented” in the traditional sense in 1879 by Thomas Edison, even though he could be said to have created the first commercially practical incandescent light. In 1878, Thomas Edison began a serious research to develop a practical incandescent lamp. Edison filed his first patent application for “Improvement In Electric Lights” on October 14, 1878. To improve upon his original design, he continued to test several types of material for metal filaments. By Nov 4, 1879, another U.S. patent for an electric lamp “a carbon filament or strip coiled and connected to platina contact wires” was filed. The patent was described with several ways of creating the carbon filament including using “cotton and linen thread, wood splints, papers coiled in various ways,” but not until several months after the patent was granted that Edison and his team discovered that a carbonized bamboo filament could last over 1200 hours. Modern incandescent bulbs are not energy efficient – less that 10% of electrical power supplied to the bulb is converted into visible light the remaining energy is lost as heat.

Lighting in building

Lighting has a direct effect on our life quality. Our mood, desirability of spaces and sense of well-being can be contributed by good lighting. A beautiful room can look bad because of bad lighting and an ugly space can get much better looks when the lighting is good. Good lighting also brings positive effect that may be importance to life quality and can affect comfort, productivity and human health as well. About 20% of energy consumption in a building goes to lighting, averagely. Take the time to have an eye for energy efficiency in a lighting plan and do not underestimate its value. More than one prove that shows the quality of light in a building affects the people in it. Hence, the productivity and satisfaction of people in a building can be positively influenced by a well-designed lighting plan. People are mostly attracted to well-lit public facilities, commercial complexes or parks. Good lighting improves ones’ mood and desirability of such spaces and can contribute greatly to a sense of well-being. Good lighting in buildings also can help people to see what is around them, identify signs and spaces, see others faces and participate in activities. Meanwhile, bad lighting can increase anxiety and may lead to trip and fall accident if people cannot make sense of what ahead of them.

Luxmeter

Lux is a measurement of the overall intensity of light within an environment for any given area or distance from the source, also known as amount of light in an enviroments perceived by the human eye. Quantity and quality of performances in workers and student affected by the quality of light in a building. In other words, lux is a nit measurement of brightness or to be more exact, illuminance.

Measuring lighting or the illumination of an environment requires the use of an incident Lux meter. Lux meter is a device for measuring brightness. It measures the intensity with which the brightness appears to the human eye specifically. This is different than measurements of the actual light energy produced by or reflected from an object or light source. A lux meter works by using a photo cell to capture light. The meter then converts this light to an electrical current. Measuring this current allows the device to calculate the lux value of the light it captured. The lux meter’s calculation of illuminance is done by using the Point Source process. The measure of the lux light meter varies depending in the light’s intensity and distance. If a point source has no reflection, a portion of the produced light reaches a surface. It is the basic lux meter working principle. Analog lux meters display values on a dial usually with a needle or pointer whereas digital devices display values as number letters. A Lux meter may be portable or bench type. Selecting lux meters or light meters requires certain performance specifications include photocell, illumination range, Lux resolution, operating temperature and foot candle resolution.

The Light Intensity Meter with Protective Cap – 0560-0540 is a light meter that has a sensor deigned to the spectral sensitivity of the eye. This makes 0560-0540 the ideal meter to be used to measure light intensity in a building. The unit as a quick read out, hold function, max/min features and a protective cap making it perfect to be used as a portable meter to be measure multiple light sources ain a building quickly with ease.

1 Foot candle = 10.7608 Lux

1 Lux = 0.09293 feet candle

How to measure light intensity using lux light meter.

• Compute for the square of the distance and multiply it by Pi and then by four. The outcome must be a radius identical to the specific space from the source. This calculation is the area of sphere at a particular distance.
• Divide the light concentration in lumens by the spherical area. The product is the illuminance in foot-candles or lux, depending on whether feet or meters were used.
• Application of a correction factor is needed if the light reaches the surface at an angle less than 90 degrees. This can be done by multiplying the computed illuminance value by the cosine of the off-axis angle.
• Keep the light source one foot away from the light sensor
• Now switch on the lux meter
• Note down the reading from lux meter

Safety guidelines

• In case of digital Lux meter, it is necessary to replace battery when the meter shows battery low.
• The meter should ever not be placed in water deep enough to submerge any part of the upper body of the meter. This will ruin the meter.
• Do not store the instrument where temperature or humidity is excessively high.
• The measurement points should not be to close to walls or obstructions.
• Daylight should be shielded by blinds or curtains when assessing artificial lighting only.

References

1. https://www.enotes.com/homework-help/what-difference-artificial-light-natural-light-653362
2. https://www.patioenclosures.com/benefits-of-natural-light.aspx
3. https://sites.google.com/a/canacad.ac.jp/comparing-and-contrasting-natural-and-man-made-light/advantages-of-man-made-light
4. https://www.bulbs.com/learning/history.aspx
5. https://blog.kreon.com/importance-of-lighting-architectural-design
6. https://dementia.stir.ac.uk/design/virtual-environments/importance-design/importance-lighting
7. http://www.acmasindia.com/blog/lux-meter/
8. https://www.yourelectricalguide.com/2019/05/lux-meter-working-principle.html
9. https://www.instrumentchoice.com.au/emails/Monthly%20Newsletter/10-10-17/how-does-a-lumen-lux-meter-work