das  Lux

B2

Estimated CEFR level.

/lʊks/

💡 What does 'das Lux' mean?

Das Lux (symbol: lx) is the SI unit of illuminance (die Beleuchtungsstärke). It indicates how much luminous flux (measured in lumens) falls on a specific area.

Simply put: 1 Lux = 1 Lumen per square meter (lm/m²).

So, it describes the brightness arriving at a surface, not the brightness emitted by a light source (that would be luminous intensity in candela).

🚨 Attention: Although 'Lux' comes from the Latin word for light (lux), the German word is neuter: das Lux.

🧐 Grammar of 'das Lux' in Detail

The word 'Lux' is a noun of neuter gender (sächlich). It's primarily used in the singular as it denotes a unit of measurement. A plural form is uncommon but formally possible ('die Lux').

Declension (Singular)

Declension (Plural - rare)

Example Sentences

1. Für Büroarbeitsplätze sind mindestens 500 Lux empfohlen.
   (At least 500 lux are recommended for office workstations.)
2. Die Beleuchtungsstärke wird in Lux gemessen.
   (Illuminance is measured in lux.)
3. Ein sonniger Tag kann über 100.000 Lux erreichen.
   (A sunny day can exceed 100,000 lux.)
4. Mit diesem Messgerät bestimmen wir die genauen Lux-Werte.
   (With this measuring device, we determine the exact lux values.)

Where is 'das Lux' used?

Das Lux is used whenever the brightness on a surface needs to be specified:

• Lighting technology & design: To define minimum brightness levels for workplaces (Arbeitsplätze), living spaces (Wohnräume), streets (Straßen), etc.
• Photography & cinematography: To measure ambient light and set exposure.
• Biology & agriculture: To determine light intensity for plant growth (e.g., in greenhouses - Gewächshäuser).
• Museums: To protect light-sensitive exhibits (lichtempfindliche Exponate) from excessive illuminance.

It's important not to confuse das Lux (illuminance - Beleuchtungsstärke) with das Lumen (luminous flux - Lichtstrom, total amount of light from a source) or die Candela (luminous intensity - Lichtstärke, light in a specific direction).

🧠 Mnemonics for 'das Lux'

For the article: Think of the German word for light: das Licht. Light is measured in Lux. Therefore: das Lux.

For the meaning: Lux sounds like the English word 'looks'. You need light (measured in Lux) to 'look' at things. Or simply remember that Latin 'lux' = light. Das Lux measures the intensity of light on a surface.

🔁 Similar & Opposite Concepts

Potential for Confusion:

• Lumen (lm): Unit for luminous flux (Lichtstrom - total light amount).
• Candela (cd): Unit for luminous intensity (Lichtstärke - light in one direction).
• Luxus (German): A completely different word meaning 'luxury'.

😄 A Little Light Joke

German: Fragt der Lehrer: "Was ist die Einheit der Beleuchtungsstärke?" Schüler: "Äh... Moment... das liegt mir auf der Zunge... Lux!" Lehrer: "Fast! Es heißt das Lux!" Schüler: "Ach so, ich dachte, es wäre ein Luxus, das zu wissen!"

English Translation: The teacher asks: "What is the unit of illuminance?" Student: "Uh... wait... it's on the tip of my tongue... Lux!" Teacher: "Almost! It's das Lux!" Student: "Oh, I thought it was a luxury (Luxus) to know that!"

📜 Poem about 'das Lux'

German:
Die Sonne scheint, der Tag ist hell,
viel Licht fällt auf die Erdenschwell'.
Wie misst man das, fragst du dich fix?
Die Antwort lautet schlicht: mit das Lux!

Auf Tisch und Wand, im ganzen Raum,
erfüllt das Licht den Menschentraum.
Ein Wert, der Helligkeit uns weist,
in Lux gemessen, wie es heißt.

English Translation:
The sun shines bright, the day is clear,
Much light falls on the earthly sphere.
How measure this, you ask with speed?
The answer's simple: with das Lux indeed!

On table, wall, throughout the space,
The light fulfills the human race.
A value showing brightness' ways,
In Lux measured, through all our days.

❓ Riddle Time

German:
Ich messe Licht, doch bin kein Strahl,
auf Flächen sag ich meine Zahl.
In Lumen pro Quadrat geübt,
bin als 'das ____' weltweit beliebt.

English Translation:
I measure light, but am no beam,
On surfaces, I state my theme.
In lumens per square meter skilled,
As 'das ____' the world I've thrilled.

(Solution: Lux)

✨ Other Information

• Etymology: The word 'Lux' comes directly from the Latin word lux, meaning 'light'.
• SI Unit: Lux is a derived unit in the International System of Units (SI).
• Practical Examples: A candle at a distance of 1 meter produces about 1 lux. An overcast day is about 1,000 lux. Direct sunlight can exceed 100,000 lux.