3.9.6　Analysis and questions

(1)After correctly connected the circuit,close the switch and adjust the value of comparison arm R0.

①Which part in the circuit goes wrong if the galvanometer pointer does not move,no matter how you adjust the bridge?(https://www.daowen.com)

②Which part in the circuit goes wrong if the galvanometer pointer always deflects to one direction?

(2)Both the bridge balance and the short circuit of the galvanometer can lead to no deflections of the galvanometer pointer.How to distinguish these two phenomena?