中考物理冲刺复习-电学总复习-专题6-电学中的比例法训练VIP专享VIP免费

ideological and theoretical qualities and practical working ability, and strive to build a contingent of league cadres with positive work style and high quality. Hold a regular meting of the party secretary every fortnightly, arrange the work of the regiment, fedback the student information. Focus on training junior high school, junior high school secretary of the regiment branch to enable them to raise A firm political conviction, diligent and diligent learning spirit and practical and innovative work style.6:电学中的比例法什么情况下用比例法比较好？ 用比例法解题要点： 例题 1： 如图，电源电压不变，开关 S 由断开到闭合，电流表两次示数之比为 2∶7 ， 则 电 阻 R1∶R2 ＝ ______ ， R1 和 R2 电 功 率 之 比 P1∶P2 ＝_______，开关断开闭合时 R1的电功率之比 P1∶P1′＝______，开关闭合时 R1的电功率和电路总功率之比 P1∶P＝_____． 例题 2： 如图，当变阻器滑片从 A 点滑到 B 点时，R1两端的电压比为 2∶3，变 阻 器 两 端 电 压 比 UA∶UB ＝ 4∶3 ． （ 电 源 电 压 不 变 ） 求 ：IA∶IB，RA∶RB，P1∶P1′，PA∶PB，R1∶RA 例题 3： 如图所示，电源电压保持不变。只闭合 S1时，电路中电流为 I1，R1的功率为 P1，R3的功率 P3为 4W；只闭合 S2时，电路中电流为 I2，R3的功率为 P3/。若 P1∶P3 / =4∶9，I1∶I2=2∶3。求：⑴电阻 R2和 R3之比；⑵这Strengthen the team connection, strengthen the knowledge education among the students (especially the first grade students), and promote the formation of good school spirit with the influence of the league members. All League branches should start with recommending outstanding students as the development objects of the League, take amateur league schools as the basis, conscientiously do a good job in the work of pre-league education, league membership education, League members' vanguard exemplary consciousness education, excellent league members' e...