Fundamentals of Light

Question 1

What is the total amount of visible light emitted by a source?

Answer 1

Luminous Flux (Lumen, lm)

Luminous flux quantifies the perceived power of light.

Question 2

What is the measurement of how much light falls on a surface?

Answer 2

Illuminance (Lux, lx)

Illuminance is important for determining the adequacy of light for tasks.

Question 3

What is the brightness perceived from a surface?

Answer 3

Luminance (cd/m²)

Luminance is a measure of the amount of light that is emitted or reflected from a surface.

Question 4

What is the term for the warmth or coolness of light, measured in Kelvin (K)?

Answer 4

Color Temperature

Color temperature helps to describe the visual appearance of light.

Question 5

What lighting property determines how accurately colors appear under a light source?

Answer 5

Color Rendering Index (CRI)

CRI values range from 0 to 100, with higher values indicating better color accuracy.

Question 6

What type of light has a lower color temperature (2,700K - 3,000K) and appears yellowish?

Answer 6

Warm Light

Warm light is often used in residential settings for a cozy atmosphere.

Question 7

What type of light has a higher color temperature (5,000K - 6,500K) and appears bluish?

Answer 7

Cool Light

Cool light is commonly used in work environments for better visibility.

Question 8

A light source with a CRI of 100 produces what kind of color accuracy?

Answer 8

Natural color accuracy (similar to sunlight)

This level of CRI is ideal for tasks requiring precise color differentiation.

Question 9

What does a low CRI value indicate?

Answer 9

Poor color rendering and inaccurate color perception

Low CRI can distort the appearance of colors in a space.

Question 10

What measurement unit is used to express illuminance?

Answer 10

Lux (lx)

Lux is derived from lumens per square meter, giving a sense of light intensity on surfaces.