Lumens are primarily used to quantify brightness for which device type?

• A. Projectors
• B. Monitors
• C. Smartphones
• D. Speakers

Answer: (A)

Lumens measure the total light output from a device. For projection, the brightness of the image on a screen depends on how much light the projector emits, so lumen ratings are the standard way to compare how bright different projectors will look in the same room. Displays like monitors and smartphones emit light themselves, and their brightness is usually described in nits (luminance per unit area) rather than total lumens. Speakers aren’t about light at all. So lumen ratings are most relevant for projectors.