ljusintensitets

Ljusintensitet is a Swedish term that translates to luminous intensity in English. It is a fundamental photometric measure of the apparent brightness of a light source in a particular direction. Specifically, luminous intensity quantifies the amount of visible light emitted by a source per unit solid angle.

The SI unit for luminous intensity is the candela (cd). One candela is defined as the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 x 10^12 hertz and that has a radiant intensity in that direction of (1/683) watts per steradian.

Luminous intensity is a directional quantity, meaning it can vary depending on the angle from which the light source is viewed. This is in contrast to luminous flux, which measures the total amount of visible light emitted in all directions. Luminous intensity is particularly useful when describing the performance of directional light sources such as spotlights, headlights, and LEDs. It helps engineers and designers understand how much light is being projected in specific directions, which is crucial for applications like illumination design and visual signaling.