(2)① Assuming that the rated voltage of the bulb is 2.5V and the rated current in the table is 0.20A, the power p = UI = 2.5v× 0.20a = 0.5w 。
As can be seen from the table, the greater the voltage, the greater the current, that is, the brighter the light bulb. Therefore, the greater the power consumed by a small bulb, the stronger the luminous brightness of the bulb.
(3) The stronger the filament illumination, the higher the filament temperature, and the greater the calculated resistance, indicating that the filament resistance is affected by temperature, and the higher the temperature, the greater the resistance.
So the answer is: (1) The light bulb is on; .
(2)①0.5; ② The greater the power consumed by the bulb, the brighter the brightness of the bulb; (3) The resistance of tungsten filament of bulb is greatly influenced by temperature. The higher the temperature, the greater the resistance of tungsten wire.