This is regulated by nipping the discharge-tube with the spring clothes pin supplied for the purpose.
|discharge tube |
A closed vessel having electrodes at either end and containing a gas at low pressure. When a sufficient voltage is applied to the electrodes, an electric current flows through the gas. Discharge tubes can be used to prevent current flow below a certain voltage; they can also function as lamps by the use of ionizing gas, which glows when current flows through the tube.