A student is presented with five identical resistors, each of resistance R0=120Ω. Two of the resistors are first connected in series to form Group A. The remaining three resistors are connected in parallel to form Group B. Groups A and B are then connected together between terminals X and Y.
Answer the following questions about this network.
(1) Identify whether Groups A and B are themselves connected in series or in parallel between terminals X and Y. Justify your answer in terms of the current that can flow through each group.
(2) Without performing any detailed numerical calculation, explain whether the equivalent resistance between X and Y is greater than, less than, or equal to R0. Support your reasoning qualitatively.
(3) Suppose one resistor in Group B fails and its resistance doubles while the other two resistors in Group B remain at R0. State and qualitatively justify whether the overall equivalent resistance between X and Y increases, decreases, or stays the same compared with its original value.