12014芜湖一中自主招生考试物理试卷答案一.单项选择题(每小题4分,共36分)题号123456789答案BCACCBDBA二.辨真伪,正确的打“√”,错误的打“×”,每问3分,共15分。题号1011121314答案×√√√×三.填空、作图和实验(每空4分,共28分)15.16.悬外浸入24=KD17.g3(M+m);18.左四.计算题(9+14+18=41分)19.(9分)解:由2UcmtR得21UtcmRR即01305=4.5RR解的-31=3.710270(/℃)20.(14分)解:(1)WF=22FnlnFl(4分)(2)1FF(4分)(3)当n=1,21/2Fmg~火线零线光控开关声控开关楼道电灯2当n=2,22()3224mmFgmg当n=3,233()74=28mmFgmg当动滑轮个数为n时,2212nnnFmgn=1,2,3(6分)21.(18分)解:(1)电压表的读数先变大后变小(3分)电流表的读数始终变大(3分)(2)○12223232313133123123313133122323()()24=()RRRRRRRRRRRRRRRRRRRRRR并易知,R并先增加后减少,故电压表示数先变大后变小(4分)○2对于电流表的读数3312AUIRRR并又231233131233121312331123312331123()()=+R()()()()RURRRRRRRRUUURRRRRRRRRRRRRRR并并并故31312331123()()RUIRRRRRRR则123233131()1()ARRRRRRIRU当滑片从a滑动到b过程中31R增大,则1AI减小,故AI增大(8分).