Illumination Principles

What does the term 'luminaire' refer to according to BS 7671?

• A device that only includes lamps.

• A type of light source used exclusively outdoors.

• A tool used for measuring luminous intensity.

• Equipment which distributes, filters or transforms light excluding the lamps themselves.

What is the unit of measurement for luminous intensity?

• Lumen

• Candela

• Lux

• Watt

What does luminous flux measure?

• The distance light travels.

• The angle of light source.

• The total amount of light energy radiated from a light source.

• The resistance to light flow.

How is illuminance measured?

• Candela per square meter

• Lumens per square meter

• Lux

• Both B and C are correct

What law defines the relationship between irradiance from a point source and distance?

• Ohm's law

• Inverse square law

• Newton's law

• Cosine law

What is the illuminance directly below a lamp of 450 candela suspended 3 meters above a bench?

• 50 lux

• 150 lux

• 450 lux

• 900 lux

What recommended lighting level is specified for technical drawing rooms?

• 1000 lux

• 500 lux

• 300 lux

• 750 lux

According to the cosine law, what happens to illuminance when the luminous flux strikes the surface at an angle other than 90°?

• It decreases.

• It increases.

• It remains unchanged.

• It doubles.

How many lamps are required for an office measuring 50m x 20m with each lamp having an LDL output of 16,000 lumens, given the illumination required is 500 lux?

• 105 lamps

• 50 lamps

• 200 lamps

• 75 lamps

What does the inverse square law formula E = I/d^2 calculate?

• Luminous intensity

• Luminous flux

• Illuminance

• Lamp efficiency