Explanation:

The unit of luminous flux is the lumen. Luminous flux measures the total amount of visible light emitted by a source per unit of time. It is also known as the total luminous power. Luminous flux is different from luminous intensity, which measures the concentration of light in a specific direction.

Luminous Intensity:
Luminous intensity is a measure of the amount of light that is emitted in a particular direction. It is the power emitted per unit solid angle. The unit of luminous intensity is the candela (cd). Luminous intensity is used to describe the brightness of a light source or the intensity of light in a specific direction.

Luminous Flux:
Luminous flux, on the other hand, measures the total amount of light emitted by a source in all directions. It is the sum of all the light that is emitted by a source, regardless of the direction. The unit of luminous flux is the lumen (lm). Luminous flux is used to describe the total amount of light emitted by a light bulb or any other light source.

Relationship between Luminous Intensity and Luminous Flux:
Luminous intensity and luminous flux are related to each other. Luminous flux can be thought of as the total luminous intensity emitted by a source in all directions. It is the sum of all the light emitted by a source, taking into account the directionality of the light.

Conclusion:
In summary, the unit of luminous flux is the lumen. Luminous flux measures the total amount of visible light emitted by a source per unit of time. Luminous intensity, on the other hand, measures the concentration of light in a specific direction.