How does an incandescent lamp generally produce light?

An incandescent lamp produces light primarily by heating a wire filament, typically made of tungsten, until it glows. This process occurs when an electric current is passed through the filament, which has a high resistance. As the current flows, the resistance causes the filament to heat up to temperatures around 2,200 to 3,000 degrees Fahrenheit. At these high temperatures, the filament emits visible light, creating the warm glow characteristic of incandescent bulbs.

The other options represent different methods of producing light. Chemical reactions can be involved in other types of light sources, such as in chemical lanterns or glow sticks, but they do not apply to incandescent lamps. Passing gas through glass is a method used in gas discharge lamps, such as neon lights, and is also not relevant to incandescent lighting. Electric discharges occur in fluorescent and arc lamps where electricity passes through a gas to produce light, but this again does not relate to how incandescent lamps operate. Thus, the method of heating a wire filament is specific to incandescent lighting technology.