电路如图所示，开关原合在位置1，t=0时，开关由位置1合向位置2，求t≥0时的<img src="https://storage.tutusouti.com/pzst/question_bank/res/1d/f6/1df6dff9d087634859f25ab30d312415b6119a50.jpg?x-oss-process=image/sharpen,200"/>=（）V。<img src="https://storage.tutusouti.com/pzst/question_bank/res/1e/5c/1e5ca58ca03eaabe360119be19997b0dd704aebd.jpg?x-oss-process=image/sharpen,200"/>