(2) If the switches S 1 and S2 are closed at the same time, the circuit is a simple circuit of R0, and the current represents the digital I2, then the power supply of the power supply is U = I2R0.

If switch S 1 is closed, switch S2 is opened, the circuit is R0 and Rx in series, and the ammeter indicates I 1, then the total resistance in the circuit is R = UI1= I 20I1;

Therefore, Rx=I2R0I 1-R0=(I2? I 1)R0I 1。

So the answer is: (1) the connection is as shown in the above figure; ②(I2？ I 1)R0I 1。