If you could only see the lights in the circuit and the wires were covered from view, how could you determine the type of circuit the lights are arranged in? a) if all the lights are equal brightness, it is a series circuit. b) if you add another bulb and it gets dimmer, it is a parallel circuit. eliminate c) unscrew one light, if the others remain on it is a series circuit. d) unscrew one light, if the others remain on it is a parallel circuit.