Question

有一待測的電阻器R_x，其阻值約在40～50Ω之間，實驗室準備用來測量                   

該電阻值的實驗器材有（圖1）：                                                                                

電壓表V（量程0～10V，內(nèi)電阻約20kΩ）                                                                

電流表A₁（量程0～500mA，內(nèi)電阻約20Ω）                                                            

電流表A₂（量程0～300mA，內(nèi)電阻約4Ω）                                                             

滑動變阻器R₁（最大阻值為10Ω，額定電流為2A）                                                  

滑動變阻器R₂（最大阻值為250Ω，額定電流為0.1A）                                              

直流電源E（電動勢為9V，內(nèi)電阻約為0.5Ω）                                                          

電鍵及若干導線                                                                                                         

實驗要求電表讀數(shù)從零開始變化，并能多測出幾組電流、電壓值，以便畫出I﹣U圖線．            

a．電流表應選用                                                                                                        ．（選填器材代號）

b．滑動變阻器選用                                                                                                     ．（選填器材代號）

c．請在方框內(nèi)畫出實驗電路圖（圖2），并將右圖中器材連成符合要求的電路．        

        

                                                                                                                                 

Answer 1

（a）A₂  （b）R₁  （c）見上圖