Electrical circuits with resistors and a single energy storage element – a capacitor or inductor are called first-order circuits. They are described by a first-order differential equation that relates input and output signals. RC circuits are used in relaxation oscillators like neon lamp oscillator circuits. When voltage is applied, the capacitor starts charging, and the lamp acts as an open circuit. As the capacitor reaches the required voltage to ionize the neon gas, the lamp becomes a short circuit. The capacitor discharges, creating a flash, and the process repeats. The time interval between the flashes depends on the time constant, adjustable by tuning R and C values. In tube lights, an RL circuit is utilized, with a choke as the inductor and the inherent wire resistance functioning as the resistor. Upon voltage application, the choke resists sudden current increases, generating an emf that increases with applied voltage. This emf ionizes the gas, illuminating the tube light. In an RL circuit the inductance over resistance is the time constant.