(2) (1) According to the circuit diagram, when the voltmeter indicates 0, the current in the circuit is the largest, and the ammeter indicates that it is not 0, so the sixth set of data has errors;
② As can be seen from the table, the current I in the circuit is 0. 1A when U2=5V, and I=0.2A when U2=4V.
∫ The total voltage in the series circuit is equal to the sum of the sub-voltages, and the power supply voltage remains unchanged.
∴u=5v+0. 1a×r 1=4v+0.2a×r 1,
Solution: r1=10Ω, u = 6V.
③ The total resistance in the series circuit is equal to the sum of all resistances,
According to ohm's law, the current in the circuit:
I = ur 1+R2 = 6v 10ω+R2,
Electric power consumed by sliding rheostat:
P2 = i2r 2 =(6V 10ω+R2)2r 2 =(6V)2( 10ω)2r 2+20ω+R2,
∵ In mathematics, a+b≥2ab,
∴( 10ω)2r2+r2≥2( 10ω)2r2×r2=20ω,
That is, when (10Ω) 2R2 = R2, R2 =10Ω, the sliding rheostat consumes the largest electric power.
So the answer is: AC or AD; 6; 10; 10.