题干

中国科技馆“探索与发现”A展厅中有一件展品为“自制变压器”,它向参观者展示了变压器的工作原理.电缆的一头已经和电压表的一极固定连好,小丽拿起电缆的另一头与电压表的另一极相连,发现电压表指针偏转了,如图甲所示.小明也来体验,他将电缆在金属柱上又多绕了几圈,然后再与电压表的另一极接好,如图乙所示,发现此时电压表指针的偏转角度与小丽体验时有所不同.根据上述情景,请你提出一个可以探究的科学问题.

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答:电压的大小与导线的圈数有关吗?

同类题4


 We all know that exercise is good for your health. But some kinds of exercise may be better than others. Running, for example, may help to protect against heart disease and other health problems. Running may also help you live longer.

 Recently, researchers studied more than 55,000 adults. About a quarter of the adults have a good habit of running. The study found these runners were much healthier than non-runners. In fact, the runners lived, on average(平均), three years longer than the non-runners.

 Running may be good exercise, but it can be difficult on the body. Here are commonly shared ideas among fitness experts(健身专家) to lower the risk of injury(受伤) for people who are new to running.

⊙Take it easy.

 Do not run too much, too soon or too fast. Most people get running injuries when they push themselves too hard. The body needs time to get used to increases in distance(里程) or speed.

⊙ Get good running shoes.

 There is no single best shoe for every runner. You should find the shoe that offers the best fit and support for your feet. More importantly, you should have a new pair of shoes every 500 to 800 kilometers.

⊙Take good notes.

 Take time after each run to write down notes about what you did and how you felt. Look for things that happen again and again. For example, you may find that your knees hurt when you run sometimes. But perhaps you feel great when you have a rest between running days. These notes will help you make the best plan for running.