Fixing faulty circuits

The path current flows through a filament bulb can be traced, from one connection and through the filament to another. In a faulty filament bulb, the filament is broken and current cannot flow through it. A circuit is not complete if there are any gaps in the circuit, or hidden in faulty wires or components. A wire or component can be tested by putting it into a simple circuit with a battery and bulb. A circuit with one faulty component will work if a wire is used to bypass the faulty component.