Lighting Up Trivia Quiz

Answer: Lux

The rate at which light is emitted by a lamp is the luminous flux, which is measured in lumens. The amount of luminous flux radiating in a particular direction is measured in candelas, and the illuminance is the amount of luminous flux falling on a given surface.

Answer: Mercury Vapour

The fluorescent lamp is a low-pressure mercury vapour lamp. Fluorescent lamps are generally used in office lighting. Neon lighting is generally the brightly coloured lighting used to accentuate buildings. (Think Las Vegas).

Answer: Incandescent lamp

Fluorescent lamps, high pressure mercury vapour lamps and sodium vapour lamps are all known as discharge lamps. Discharge lamps have a negative current/voltage characteristic, which means that a current supplied at a constant voltage will increase in intensity until it destroys the lamp. A ballast limits the current.

Answer: High Pressure Sodium

A high pressure sodium (HPS) lamp has a typical efficacy of 90, while an incandescent lamp has an typical efficacy of only 15. However, although a HPS lamp gives out more light, the colour is not as good as the other lamps, which only makes it suitable for certain installations.

Answer: Metal Halide

Metal halide has a good trade off between efficacy and colour rendering. The best colour under lights would be obtained by the use of incandescent lamps, however, the installed wattage would be at least 5 times more. Metal halide also has a far better colour rendering than HPS or mercury lamps.

Answer: All the reasons listed

The use of electronic control gear in fluorescent luminaires is becoming the accepted norm, due to the above reasons, and others, including higher lamp output, constant lamp performance, and better power factor. Electronic control gear and transformers are also used for other lamp types.

Answer: Ingress Protection

The two digits of the IP rating provide the rating against foreign bodies, and against water respectively. A light fitting with an IP 65 rating will be dust-tight, and protected against jets of water.

Answer: Double parabolic diffuser

The type of diffuser controls the reflected glare. A light fitting reflecting onto a computer monitor can be disturbing. A double parabolic diffuser limits the angle of the light from the fitting to less than 60 degrees, preventing glare.

Answer: Halogen

Although halogen lamps are available at mains voltage, these are more expensive than the 12 Volt lamps, and are more susceptible to voltage fluctuations. Incandescent lamps operate at mains voltage, and ballasts are required for tubular fluorescent lamps and compact fluorescent lamps. (Some compact fluorescent lamps have the ballast built into the base).

Answer: All are important

Other factors to consider are glare limitation, the direction of the light, visual comfort, uniformity, quantity of light required, the IP rating of the fitting, and any special requirements for emergency lighting and hazardous area lighting. If you chose "Lighting Cost", then you are probably an accountant or a quantity surveyor.