When the slider P of the sliding rheostat slides to the B end, the brightness of the small bulb will gradually become brighter and the resistance will become smaller, so the left A end should be connected below, as shown in the figure:
(2) The ammeter pointer is reversed, indicating that the positive and negative poles are reversed;
(3) In order to make the wire connection more firm, the winding direction should be consistent with the screw tightening direction, and it should be wound up, otherwise it will fall off easily, so the C diagram is correct;
(4) According to the data in the table, when U=2.5V, I=0.22A, so P = UI = 2.5v× 0.22a = 0.55w
The greater the voltage, the greater the current, the greater the electric power and the greater the resistance. It can be seen that the resistance of the filament increases with the increase of temperature.
So the answer is: (2) the positive and negative poles are reversed; (3)C； (4)0.55; The filament resistance increases with the increase of temperature.