(2004? After learning ohm's law, the teacher asked the students to design a circuit to measure the unknown resistance Rx. The circuit designed by 1 is as follows.

(1) When S is closed and S 1 is open, the current through R0 is I; When s and S 1 are closed, the total current in the circuit is I 1, and the current through RX is I1-I;

R0 and RX are connected in parallel, and the voltages on the two resistors are equal. R0I=RX(I 1-I) exists because the power supply voltage is constant.

RX=IR0I 1？ I

(2) Because there will be errors in the experiment, in order to reduce the errors, we can adopt the method of measuring several groups of average values, select the sliding rheostat, and measure the resistance by voltammetry. The circuit diagram is as follows:

(3) The advantage of designing the circuit by voltammetry is that a sliding rheostat is added to protect the circuit, which can make the data measured many times in the experiment average.