例某同学利用电源、电流表、电压表、开关,标有“50 Ω2 A”字样的滑动变阻器和若干导线测定小灯泡的额定功率,其中灯泡上所写“0.3 A”字样清晰可见。电压表0～15 V档损坏,小灯泡的额定功率估计为1.5W左右,该同学实验步骤正确。当闭合电键时,电压表和电流表的示数分别为2 V和 A classmate used a power supply, an ammeter, a voltmeter, a switch, a sliding rheostat marked “50 Ω 2 A”, and a number of wires to measure the rated power of a small light bulb, where the “0.3 A” written on the bulb was clearly visible. The voltmeters 0 to 15 V are damaged, and the rated power of the small light bulb is estimated to be about 1.5 W. The student’s experimental procedure is correct. When the key is closed, the voltmeter and ammeter are shown as 2 V and