Why Do Incandescent Lightbulbs Get Brighter Right Before They Burn Out?

Think back to the last time you walked into a room, flipped the light switch, and were greeted by a bright flash from the light and then darkness. Your lightbulb just burned out. Nothing lasts forever, but why do lightbulbs give off that big flash before they die? Light bulbs have a thin filament through which electricity flows, and while the bulb is working current flows through the supply wires and the filament. If the filament breaks while current is flowing through it, its ends move from one another and an electric arc starts. Once the arc starts, it ionizes the surrounding gas, which allows for much higher currents to flow through the thin filament. The intensive arc is what produces a bright flash and causes the bulb’s filament to explode. The circuit is broken, the arc stops, and you now need a new lightbulb.