Candela

High school (ages 12+)
Science & Technology

Name:

Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/candela

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. What is a candela?A candela is the unit that tells us how bright a light is in a particular direction. It measures the light power that comes out of a point source, like a flashlight, into a specific cone of space. The unit is called cd for short.
2. Why do scientists use candela instead of just counting light?Because candela focuses on how bright light is in one direction, not all the light it gives off. This helps engineers design safe street lights and bright screens that look good from the right angle.

Luminous Intensity: The measure of the perceived power emitted by a light source in a particular direction, measured in candelas.
Solid Angle: A three-dimensional angle that describes the extent of a cone or pyramid, measured in steradians (sr).
Luminous Efficacy: The ratio of luminous flux (lumens) to radiant flux (watts), indicating how efficiently a light source produces visible light.