CLD Lighting Fundamentals 2

Question 1

Which photometric quantity describes the total light output of a source in all directions?

Accepted Answer

Luminous flux

Answer

Luminous flux, measured in lumens (lm), represents the total quantity of visible light emitted by a source in all directions.

Question 2

A light source has a color temperature of 2700K. How would this light typically be described?

Accepted Answer

Warm white

Answer

2700K falls in the warm white range, producing a yellowish-amber tone similar to incandescent lamps.

Question 3

What is the inverse square law in lighting?

Accepted Answer

Illuminance decreases as the square of the distance increases

Answer

The inverse square law states that illuminance (E) decreases proportionally to the square of the distance (d) from a point source: E = I/d².

Question 4

What term describes the ratio of luminous flux reflected by a surface to the flux incident upon it?

Accepted Answer

Reflectance

Answer

Reflectance is the ratio of reflected luminous flux to incident luminous flux, expressed as a decimal or percentage.

Question 5

Which of the following best defines 'luminous efficacy' of a light source?

Accepted Answer

Lumens per watt (lm/W)

Answer

Luminous efficacy is the ratio of luminous flux output to electrical power consumed, expressed in lumens per watt (lm/W).

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