Xiao Huang used the circuit shown in Figure (a) to verify the "relationship between current and resistance". The equipment used is: 3V constant voltage power supply with resistance values of 5ω and 10ω. (1) According to the meaning of the question, if the power supply voltage is 3V, the voltmeter can only choose the range of 0 ~ 3v, and the maximum current in the circuit is 3v5Ω = 0.6a, so the ammeter should choose the range of 0 ~ 0.6a; Then connect the electrical appliances according to the schematic diagram. The answer is shown in the figure below:

(2)a, ammeter range is 0 ~ 0.6a, minimum division is 0.02A, and indicator pointer is 0.3A；;

C, the circuit is normal, so the wiring fault is eliminated, that is, there should be instructions in the ammeter, but the current value is too small, because the voltage at both ends of the fixed resistance is too small.

So the answer is: (2)a, 0.3; C. the voltage across the fixed-value resistor is small.