题目

 “Let’ s Talk”：The Free Advice Project A few weeks ago, I took a walk around Washington Square Park. I met all the usual people：street performers, the Pigeon Guy, a group of guitarists singing in harmony. But off to the side, sitting on a bench was a woman doing something vastly different—giving free advice. A week or two later, I set up an interview with her and we discussed her project at length. Lisa Podell, 32, started the Free Advice Project this past May. It began as an experiment; she sat in Washington Square Park for a day with a sign that read “Free Advice” as a s一台理想变压器原、副线圈匝数比为10：1，原线圈接u=100sin100πtV的交变电压，副线圈两端用导线接规格为“6V，12W”的小灯，已知导线总电阻r=0.5Ω，试求：副线圈应接几盏小灯？这些小灯又如何连接才能使这些小灯都正常发光？