Candela

Definition

Candela is the SI unit of luminous intensity, measuring the power emitted by a light source in a particular direction. It quantifies how bright a light source appears to human vision.

5 Must Know Facts For Your Next Test

1. One candela roughly equals the luminous intensity produced by a common candle.
2. Luminous intensity measured in candelas is crucial for understanding how bright a light source appears to human eyes.
3. The candela is part of the International System of Units (SI) and is essential in photometry, the science of measuring visible light.
4. The definition of candela is based on specific physical constants, including the frequency of light emitted from a black-body radiator at the temperature of solidifying platinum.
5. Understanding candelas helps in studying the sensitivity of human vision to different wavelengths and intensities of light.

Review Questions

• What does one candela represent in terms of luminous intensity?
• How is the concept of candela important in understanding human vision?
• What physical constants are used to define one candela?

Related terms

Lumen: One lumen measures the total quantity of visible light emitted by a source per unit time.

Lux: Lux measures illuminance, indicating how much luminous flux is spread over a given area.

Photoreceptor Cells: Specialized cells in the retina that respond to light and play key roles in vision.