(1) Connect two resistors in series, and voltmeters are connected in parallel to both ends of the two resistors, as shown in the figure;

(2) Choose two resistors in this experiment Resistor wires with different resistances are connected in series, and the current passing through them is the same, but the voltages at both ends are different. The purpose is to make the voltages at both ends of R1 and R2 different;

(3) The amount of work done by the current cannot be directly observed. However, the current that does more work generates more heat. The kerosene in the flask absorbs more heat and the temperature rises quickly. We can use the conversion method to compare the amount of work done by the current by observing the thermometer's display. According to W=I2Rt, we can know that the resistance The larger the value, the more work the current does, ∵R1>R2, ∴W1>W2;

(4) The conclusion drawn from the experiment: When the current is constant and the power-on time is constant, the higher the voltage, the more work the current does. The more work you do.

So the answer is: (1) The experimental circuit diagram is as shown in the figure;?

(2) Make the voltages at both ends of R1 and R2 different;

(3 ) The change in the thermometer indication, R1;?

(4) When the current is constant and the power-on time is constant, the higher the voltage, the more work the current does.