A measure of the total "amount" of visible light emitted by a source is known as what?

The total "amount" of visible light emitted by a source is quantified in lumens. Lumens provide a standard measure for luminous flux, which indicates how much light is produced by a source. This measurement is important in various applications, such as lighting design and photography, where understanding the quantity of light available is essential for producing desired effects or meeting specific standards.

Other options relate to light but serve different purposes: bright light describes an observable quality rather than a measurement; illuminance measures the amount of light that hits a surface per unit area (often in lux or foot-candles), which is not the same as the total light emitted by the source; and light intensity refers to the power of light emitted in a particular direction, typically measured in candelas. Understanding these distinctions helps clarify why lumens is the correct term for the total measurable output of visible light from a source.