题目

要增大LC振荡回路的频率，可采取的办法是（    ）A.增大电容器两极板正对面积              B.减小极板带电荷量C.在线圈中放入软铁棒做铁芯              D.减少线圈匝数 答案：解析：根据LC振荡回路的频率公式和平行板电容器电容公式知，当增大电容器两极板正对面积时，C增大，f减小.当减少极板带电荷量，不影响C，即f不变.在线圈中放入软铁棒做铁芯，L增大，f减小.减少线圈匝数，L减少，f增大.答案：DTomorrow is Father’s Day. I don’t know    . A．what can I do for my father B．what I will get for my father C．where I went with my father D．where will I go with my father