论文部分内容阅读
1.C 2.D 3.B(解析:变阻器的滑片P固定在中点,接入电路的阻值不变,变阻器相当于定值电阻,开关S的断开与闭合改变了并联部分电路的总电阻,所以灯L与电解槽并联相当于一个变阻器,与R串联;开关S断开时灯L正常发光,开关S闭合时并联部分的总电阻变小,并联部分电路的电压变小,小于灯泡的额定电压,灯泡的实际功率小于额定功率,所以灯泡的亮度变暗.故选B)4.(1)W=2 kW·h. (2)P=30 W,R=19.2Ω.
1.C 2.D 3.B (Analysis: rheostat slide P fixed at the midpoint, the resistance of the access circuit unchanged, rheostat equivalent to the value of resistance, the switch S is disconnected and closed to change the parallel part of the circuit The total resistance of the lamp, so the lamp L and electrolyzer in parallel is equivalent to a rheostat, and R in series; switch S is off when the normal light L, switch S is closed when the total resistance of the parallel part becomes smaller, parallel part of the circuit voltage becomes smaller, If the rated lamp voltage is less than the rated voltage of the lamp, the actual power of the lamp is less than the rated power, so the brightness of the lamp is dimmed, so B = 4. (1) W = 2 kW · h (2) P = 30 W, R = 19.2Ω.