Electrical Science: Illuminance, Luminance & Luminous Intensity

These flashcards cover key concepts about lighting design, including definitions and units related to illuminance, luminance, luminous intensity, and their implications in real-world applications.

What are the basic areas of knowledge an electrician needs to know regarding lighting?

Define and understand illuminance, luminance, and luminous intensity.

What does the inverse square law explain?

It explains how light behaves as it is emitted from a luminaire onto a surface.

What is the SI unit for luminous flux?

Lumen (lm) is the SI unit for luminous flux.

How does luminous flux relate to human perception of light?

It considers the human eye’s sensitivity, providing a practical measure of brightness.

What is the unit for luminous intensity?

Candela (cd) is the SI base unit of luminous intensity.

Define illuminance in terms of its unit.

Illuminance measures the amount of light falling on a surface, expressed in lux (lm/m²).

What does luminance measure?

Luminance measures the luminous intensity projected on a given area, expressed in candelas per metre squared (cd/m²).

What is luminous efficacy?

It measures the efficiency of a lamp or luminaire, comparing luminous flux to electrical power, measured in lumens per watt.

What distinguishes efficiency from efficacy in lighting design?

Efficiency is the ratio between power in and power out in the same unit, while efficacy compares light output in lumens to electrical power in watts.

Why is appropriate luminous flux important in workplaces?

It can reduce eye strain and fatigue among employees, enhancing their performance and comfort.