(1) As shown in the figure, the voltmeter is connected in parallel at both ends of the conductor, the ammeter is connected in series in the circuit, and the sliding rheostat of the protection circuit is connected in series in the circuit, as shown in the figure below:

(2) Measured physical quantities: indicator I of ammeter and indicator U of voltmeter;

(3) According to Ohm's law, the resistance of a conductor is:

R=UI，

Wire length:

s′= RR0 = ui r0，

The length of the conductor is twice the distance between the two places, so the distance between the two places is half the length of the conductor.

Then the distance between the two ends is s = s' 2 = u2IR0.

So the answer is:

(1) as shown above;

(2)U、I；

(3)U2IR0。