CLD Photometry & Light Measurement

Question 1

What unit is used to measure luminous flux?

Accepted Answer

Lumen

Answer

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

Question 2

Which unit measures illuminance, the amount of light falling on a surface?

Accepted Answer

Lux

Answer

Illuminance is measured in lux (lx) in SI units, representing lumens per square meter of surface area.

Question 3

A goniophotometer is primarily used to measure:

Accepted Answer

Luminous intensity distribution of a luminaire

Answer

A goniophotometer measures the luminous intensity distribution of a luminaire at various angles, producing photometric data used in lighting calculations.

Question 4

According to the inverse square law, if the distance from a point source doubles, the illuminance on a surface:

Accepted Answer

Decreases to one-quarter

Answer

The inverse square law states illuminance is inversely proportional to the square of the distance, so doubling the distance reduces illuminance to 1/4.

Question 5

Luminous intensity is measured in which unit?

Accepted Answer

Candela

Answer

Luminous intensity, which describes the power of a light source in a particular direction, is measured in candelas (cd), the SI base unit for photometry.

(CLD) Certified Lighting Designer Practice Test

(CLD) Certified Lighting Designer Practice Test

CLD Photometry & Light Measurement