理想变压器原、副线圈匝数比为20:1,两个分别标有“12V,6W”、“12V,12W”的小灯泡并联在副线圈的两端,当两灯泡都正常工作时,原线圈电路中电压表和电流表(可视为理想的)的示数分别是( )
A.120V,0.10A
B.240V,0.025A
C.120V,0.05A
D.240V,0.075A
答案:D
题目分析:灯泡正常工作,电压为额定电压,所以副线圈电压U2 = 12V,电流.根据变压器原副线圈电压与线圈匝数的关系得
,解得:U1 = 240V.根据变压器原副线圈电流与线圈匝数的关系得
,解得:I1 = 0.075A.所以电压表和电流表的示数分别为:240V,0.075A.故选D