One day last November, Liz Douglas went shopping. She spent hours at the supermarket. After she paid for all the things she bought, she went back to her car and put the shopping bags on the back seat (后座) of the car. Then she started to drive home.

    Ten minutes later, it began to rain heavily. Soon, Liz found it hard to see the road clearly. There was a lot of water on the road, so she drove slowly. Although Liz was an experienced driver, she felt afraid.

    突然，Liz看见她前面的一棵树并试图停车。But it was too late. Liz closed her eyes. She hoped that the airbags (气囊) in the car would work when the car hit the tree. Unluckily, they didn't.

    However, Liz was lucky. When the car hit the tree, a bag of bread flew out of one of the shopping bags. The car turned over, and the bread landed between Liz' s head and the roof(顶部) of the car. It stopped her head from hitting the roof of the car.

    About half an hour later, firefighters (消防队员) helped Liz get out of the car. They sent her to the hospital, but she went home soon because she didn't get hurt badly. Her head was free and she only had a few cuts. Liz's son went to get the things Liz bought from the car and gave the bag of bread to her. She was going to keep it as a souvenir (纪念品) because it brought her good luck.

公元前5世纪，雅典民主政治发展到顶峰，作为一个普通的成年男性公民，你最不可能遇到的是

沈仔细同学在探究“感应电流产生的条件”实验中，发现每次电流表指针的偏转角度不相同，于是他提出了“感应电流的大小与哪些因素有关”的问题，并做出以下猜想：

猜想一：感应电流的大小与磁场的强弱有关；

猜想二：感应电流的大小与导体切割磁感线的速度有关；

猜想三：感应电流的大小与切割磁感线的导体长度有关．

为验证自己的猜想是否正确，他选用的器材有：导体棒一根，10匝线圈和20匝线圈各一个（导体棒电阻与多匝线圈电阻近似相等），磁场强度不同的蹄形磁铁三块，灵敏电流表一块，长导线若干．请你帮他完成下列内容：

（1）为了验证猜想一，他做了如下实验．

①首先用图1所示的装置做实验，导体棒ab以速度v₁切割磁感线，观察并记录电流表指针偏转的格数n₁．

②调换一块磁场强度更强的磁铁，并将导体棒换成10匝线圈，线圈的一边置于磁场中，如图2所示，并以速度v₂（v₂＞v₁）切割磁感线，观察并记录电流表指针偏转的格数n₂．

请你说明他的操作中存在的问题；

（2）设计出探究“猜想二”的记录数据表格．