(20 1 1? Xuzhou) A study group wants to measure the rated current of a light bulb with a rated voltage of 2.5V The known power supply voltage is 6V. (1) The electricity they designed.

(1) In the experiment, the rated current of a bulb with a rated voltage of 2.5V should be measured, so the voltmeter is connected in parallel with the small bulb, and the ammeter is connected in series with the small bulb, as shown in the following figure:

(2) The rated voltage of the small bulb is 2.5V, and the voltage is expressed as 2.5V in the experiment, so the voltmeter should be 0 ~ 3V.

Answer: the voltmeter uses a range of 0 ~ 3 v.

(3) After closing the switch, the light bulb does not light up, indicating that the current in the circuit is too small, or there is an open circuit, which has nothing to do with the direction of the current.

A: what is unreasonable is D.

(4) As can be seen from the figure, the selected range of the ammeter is 0 ~ 0.6A, the graduation value is 0.02A, and the pointer points to the fifth battery after 0.2A, so the reading is 0.2A+0.02A× 5 = 0.3A 。

Answer: The rated current of the light bulb is 0.3A 。