Question

某實(shí)驗(yàn)小組欲測(cè)量額定電壓為3V的某LED燈在正常工作時(shí)的電阻R_x，已知該燈正常工作時(shí)電阻大約為600Ω左右．除該LED燈外，實(shí)驗(yàn)中可供選擇的實(shí)驗(yàn)器材有：                                                                

電流表A（量程0～0.6A，內(nèi)阻R_A約2.0Ω）                                                                

電壓表V₁（量程0～6V，內(nèi)阻R_Vl約5kΩ）                                                                 

電壓表V₂、（量程0～3V，內(nèi)阻R_v2=500Ω）                                                                 

滑動(dòng)變阻器R（0～20Ω，允許最大電流1.0A）                                                            

蓄電池E（電動(dòng)勢(shì)10V，內(nèi)阻約0.1Ω}）                                                                      

開關(guān)S一只、導(dǎo)線若干                                                                                                

（1）實(shí)驗(yàn)中要求測(cè)量盡量準(zhǔn)確且方便調(diào)節(jié)，除電源、LED燈、滑動(dòng)變阻器、開關(guān)和導(dǎo)線外，電表（電流表或電壓表）應(yīng)選用                                                                                                                    、         （填寫儀器符號(hào)）．

（2）將你所設(shè)計(jì)的實(shí)驗(yàn)電路圖畫在答題卡上對(duì)應(yīng)的虛線框中，并在圖中標(biāo)明儀器符號(hào)．                         

（3）寫出測(cè)量LED燈正常工作時(shí)的電阻表達(dá)式R_X=                                        （用電壓表V₁的示數(shù)U₁、電壓表V₂的示數(shù)U₂、電流表A的示數(shù)I，R_V1、R_v2、R_A中的某些字母表示）．                          

                                                                                          

                                                                                                                                   

Answer 1

（1）V₁，V₂；（2）如圖所示；（3）．