(2009? Xiaoyu found that when the circuit as shown in the figure was connected and the slider of the sliding rheostat moved to the right, the light bulb dimmed. Regardless of temperature,

AB。 When the slider moves to the right and the light bulb darkens, the resistance of the sliding rheostat connected to the circuit increases, so the sliding rheostat connects A and C to the circuit, so option B is correct;

C. When the resistance of the sliding rheostat connected to the circuit increases, the current in the circuit decreases, the light bulb darkens, and the actual power of the light bulb decreases, so option C is wrong;

D, in the circuit, the resistor converts electric energy into internal energy, and the bulb converts electric energy into internal energy and light energy, so the D option is wrong.

So choose B.