True or False: The lumen output of an electric lamp decreases with use.

The statement is true because many types of electric lamps experience a decrease in lumen output over time due to several factors. This phenomenon, known as lumen depreciation, occurs as the lamp ages and its components wear out or degrade.

In incandescent lamps, for example, the filament gradually wears down, resulting in less light being emitted. Fluorescent lamps also show lumen depreciation as phosphor coating becomes less effective with use and can accumulate dirt and dust, which further reduces light output. Similarly, LED lamps can experience a reduction in lumen output over time as they operate, largely due to heat buildup and eventual deterioration of the semiconductor material.

While some types of lamps may have varied rates of lumen depreciation, the overarching trend across many commonly used electric lamp types is a decrease in lumen output with sustained use, supporting the correctness of the answer.