Question

有一待测的电阻器R_x，其阻值约在40～50Ω之间，实验室准备用来测量                   

该电阻值的实验器材有（图1）：                                                                                

电压表V（量程0～10V，内电阻约20kΩ）                                                                

电流表A₁（量程0～500mA，内电阻约20Ω）                                                            

电流表A₂（量程0～300mA，内电阻约4Ω）                                                             

滑动变阻器R₁（最大阻值为10Ω，额定电流为2A）                                                  

滑动变阻器R₂（最大阻值为250Ω，额定电流为0.1A）                                              

直流电源E（电动势为9V，内电阻约为0.5Ω）                                                          

电键及若干导线                                                                                                         

实验要求电表读数从零开始变化，并能多测出几组电流、电压值，以便画出I﹣U图线．            

a．电流表应选用                                                                                                        ．（选填器材代号）

b．滑动变阻器选用                                                                                                     ．（选填器材代号）

c．请在方框内画出实验电路图（图2），并将右图中器材连成符合要求的电路．        

        

                                                                                                                                 

Answer 1

（a）A₂  （b）R₁  （c）见上图