Building Construction (Lighting Systems)

A ballast is a device used in conjunction with fluorescent and HID lamps to limit the amount of current flowing through the lamp. It helps regulate the electrical current, preventing the lamp from drawing too much power and potentially burning out. The ballast also ensures that the lamp starts and operates properly, providing the necessary voltage to initiate the electrical discharge in the lamp. Without a ballast, the lamp may not function correctly or may be at risk of damage.

Daylight is used where color matching is important and is equivalent to a north sky. This suggests that daylight provides a natural and balanced lighting condition that allows accurate color perception and reproduction. The reference to a north sky implies a cool and neutral color temperature, which is often desired in color-critical applications such as photography, design, and printing.

Lux is a unit of measurement used to quantify the amount of light that falls on a specific area. It specifically measures the amount of lumens that fall on an area of one square meter, which is located one meter away from the light source. Lux is commonly used to determine the brightness or intensity of light in various settings such as indoor spaces, outdoor environments, and in the field of photography.

The given description is referring to a fluorescent light bulb. Fluorescent bulbs consist of a cylindrical glass tube that is sealed at both ends and filled with inert gas, typically mercury vapor. The ends of the tube have cathodes that provide the electrons needed to start and sustain the mercury arc or gaseous discharge. This discharge produces ultraviolet light, which then interacts with the phosphor coating inside the tube to create visible light. Therefore, the correct answer is "fluorescent."

The given information about the HID field describes the newest addition, which is an arc tube made of high-density polycrystalline alumina and contains a mixture primarily consisting of sodium. Based on this description, the correct answer is High Pressure Sodium.

The given answer, "incandescent," is correct because it accurately describes the type of lamps being referred to in the provided statement. Incandescent lamps are composed of a sealed glass bulb that contains a filament. This filament is connected at its ends to the contact area in the base of the lamp, which completes the electric circuit and allows the lamp to produce light through the process of incandescence.

Metal halide lamps are a type of high-intensity discharge (HID) lamp that use a mixture of mercury vapor and metal halides to produce light. The given description matches the characteristics of metal halide lamps, such as increased light output, improved color rendition, and a small source size. These lamps are known for their bright white light and are commonly used in applications that require high-quality lighting, such as stadiums, parking lots, and retail stores.

The unit "candela" is used for measuring luminous intensity, which is the amount of light emitted or reflected from a particular source in a specific direction. It is a base unit of the International System of Units (SI), representing the brightness of a light source as perceived by the human eye. The candela is defined as the luminous intensity in a given direction of a source that emits monochromatic radiation of frequency 540 terahertz and has a radiant intensity in that direction of 1/683 watt per steradian.

Mercury vapor is a substance that, when electrically excited, emits visible light with a blue-green color. This phenomenon is known as fluorescence. The excited electrons in the mercury atoms release energy in the form of photons, which are particles of light. The specific energy levels of the mercury atoms determine the wavelength of the emitted light, resulting in the characteristic blue-green color. This property of mercury vapor is utilized in various applications, such as fluorescent lamps and neon signs.

Lumens is the unit of light or luminous flux. Luminous flux refers to the total amount of light emitted by a source, and lumens measure this flux. It is a measure of the perceived brightness of a light source, taking into account the sensitivity of the human eye to different wavelengths of light. The higher the number of lumens, the brighter the light source.

A footcandle is a unit of measurement used to quantify the amount of light illuminating a specific area. It measures the amount of lumens (a unit of luminous flux) falling on an area of one square foot located one foot away from the light source. In other words, it indicates the intensity of light reaching a surface at a specific distance.

The use of a halogen gas cycle in tungsten halogen lamps helps to prevent rapid depreciation of the lamp filament and darkening of the transparent envelope. Halogen gas reacts with the tungsten atoms that evaporate from the filament during operation, forming tungsten halide compounds. These compounds are then transported back to the filament by convection, where they decompose and release tungsten atoms again. This process helps to maintain a stable filament temperature and prevents blackening of the envelope, resulting in a longer lifespan and better performance of the lamp.

Candlepower is a unit of light intensity that measures the amount of light emitted by a source in a specific direction. It is a common unit used to quantify the brightness of light bulbs, flashlights, and other lighting devices. The term "candlepower" originated from the practice of comparing the brightness of a light source to that of a standard candle. Therefore, candlepower is an appropriate unit for measuring light intensity.

The unit of brightness is footlambert. Footlambert is a unit used to measure the brightness of a surface, specifically the luminance emitted or reflected by that surface. It is defined as the amount of light emitted or reflected by a surface that is uniformly emitting or reflecting one footlambert of luminance. This unit is commonly used in the field of lighting design and is important in determining the appropriate level of brightness for different lighting applications.

PAR lamps, also known as Parabolic Aluminized Reflector lamps, are a type of lighting fixture that contain a complete optical system within a single bulb. This system includes a filament, reflector, and lens. The reflector is designed to direct and control the light output, while the lens helps to focus and shape the light beam. R lamps, on the other hand, do not have the same integrated optical system and may not provide the same level of control and precision in light distribution. Therefore, PAR lamps are a more suitable choice when a specific and controlled lighting effect is desired.