Which kind of spectrum is found in the fluorescent bulb?

A fluorescent bulb emits a line spectrum, primarily due to the excitation of gas molecules inside the bulb. When electricity passes through the gas, it excites the atoms, causing them to emit light at specific wavelengths characteristic of the gas used, typically Mercury vapor. This results in distinct lines of color rather than a continuous spectrum, which is then converted to visible light by the phosphor coating on the inside of the bulb.