2019-2020學(xué)年度九年級物理考題精練-專題二十二：開關(guān)對動態(tài)電路的影響

2019-2020學(xué)年度九年級物理考題精練——專題二十二：開關(guān)對動態(tài)電路的影響【解題指導(dǎo)】初中電學(xué)中，電路。開關(guān)型動態(tài)電路電路的分析是極其重要的考點。在做此類題目時，要學(xué)會簡化1.當(dāng)開關(guān)斷開時，開關(guān)所在支路中無電流通過，可將該支路去掉；2.開關(guān)閉合時，因此，相當(dāng)于導(dǎo)線，同時與開關(guān)并聯(lián)的支路被短路而無電流通過，把不起作用的元件去掉，該支路也可去掉。再畫出簡化后的電在考慮動態(tài)電路問題時，可使電路簡化，路圖，往往能夠起到一目了然、事半功倍的效果。【真題演練】類型一：常規(guī)控制型1.(2019邵陽，20)如圖所示的電路中，電源電壓恒定不變，已知R＝3R，當(dāng)S和S閉合、121S斷開時，電壓表和電流表的示數(shù)分別為U和I；當(dāng)S斷開、S和S閉合時，電壓表和電21112流表的示數(shù)分別為U和I，則U：U、I：I分別是（）221212A．1：1、4：32.（2019長春，關(guān)S2，則（B．1：2、1：3C．1：1、1：4D．1：4、1：1S1，小燈泡發(fā)光，再閉合開9）如圖所示，電源兩端的電壓恒定．閉合開關(guān)）A.小燈泡變亮B.電流表示數(shù)變小D.電路的總電阻變大C.電壓表示數(shù)不變3.（2019綿陽，煲粥。小文將大米等食材放入電飯煲內(nèi)，接通27）某一天晚上睡覺前，小文同學(xué)用有預(yù)約功能的電飯煲為家人第二天早餐220V家庭電路，經(jīng)過了待機、加熱、保溫三______kWhSS1RR12R=_____24201911SS1L2S2ALLLBCD5.2019I112S2S1S3U1S2S1S3I2U2R1R2=216.201921R30R1021SS1S20.4A123SS2S1SSS2100s17.20192710VR20R30211S2SS132S3SS125min31.20197LL12SA.L1B.L1C.L2D.L22.20196V3W118RR1R202L2SSS12LAW2SSS122VR1minR11J3.201912R1R2A.S990WB.C.D.SS1R25min,3.3104JR1R218R=R=R3=101RR234.201926,2,_____I1:R1,R2,SS12III2=_____,215201927220VR1RR61.6S122440WSS12123R16.201926,,L6V2W3V,,S1R1S2,0.5AS1,0.4W:(1)(2)R11.201912RR12SS12400Ws100WR210min1.2105J2.20193S19RRR1RR21232S10.4ARP1R311.6WS2RP2PP3227122VR1R33.201916R12R6R12S13Sa20.6AbA0.3A4.2019B0.6AC0.9ASD1.2A161S12A.B.C.D.5.2019A810V10A.1B.5C.15W1AD.6.20192701122334R2421R60.5212R313281[3000r/kW?h]7.201923R110?12VR1R21S1RRS2a21.6W12R2Sb2S10s122019-20201.2.1.(201920)R3RSS112SUISSS21112UIUUII121222A1143B1213C1114D1411A2.2019S29S1A.C.CB.D.3.201927220V______kWhRRR2=_____SS112(1).0.8811(2).22042019S1S2LS2ABCDLLLC5.2019I112S2S1S3U1S2S1S3I2U2R1R2=21D6.201921R30R1012SS1S20.4A123SS2S1SSS12100s1SS1S2R1IUIR0.4A3012V112SS2S1R2I1.2A23SSS12RR12RR12II+I0.4A+1.2A1.6A21100sWUIt12V1.6A100s1920J112V23SS2S11.2ASSS2100s1920J17.20192710VR20R30211S2SS132S3SS15min231S2SS1RR+R20+3050132I0.2A2S3SS1RR2215minWt560s1000J23S2SS1P3P2WSS1S2P3RP12W1S2SS130.2A2S3SS125min1000J32561.20197LL12SA.L1B.L1C.L2D.L2D2.20196V3W118RR1R202L2SSS12LAW2SSS122VR1minR11J10.84.821024123.2019R1R2A.S990WB.C.D.SS1R25min3.3104JR1R22618BCR1=R2=R3=10RRR2R34.2019,,I,_____:,12,S1S21II1I2=_____,2(1).SS(2).41125201927220VR1RR61.6S122440WSS121231R1S1440WP=UIPI440W2AU220V2S1R1R2I=URU220VI2AR110R1R1=R-R2=110-61.6=48.4S1S23R1U2(220V)21000WP=R48.4112A23R148.41000W6.201926,,L6V2W3V,,S1R1S2,0.5AS1,0.4W:(1)(2)R11R2SS121R--------S11R1R1=3.6R1=10------R1=3.6R1=3.6R101211.2019RR12SS12400Ws100WR210min1.2105J363400192.20193SRRRRR212123S10.4ARP1R311.6WS2RP2PP3227122VR1R3122010163.2019R12R6R12S13Sa20.6AbA0.3AB0.6AC0.9AD1.2AC4.2019S116S12A.B.C.D.A5.2019A810V10A.B.C.D.1515W1AC6.20192701122334R2421R60.5212R133281[3000r/kW?h]112R2R3P23RR23P34RR1P22PP+P1++1000W2PP1000W200WPR242R3RRR24260.5181.5321QWPt200W60s1.2104J381W0.027kW?h9.72104JP810WPP11