题干

现有一根玻璃棒,不知其是否带电,请简要写出几种判断方法.
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答案(点此获取答案解析)

解:①根据带电体具有吸引轻小物体的性质判断,方法是:用玻璃棒靠近轻小物体(如通草球),若吸引,说明玻璃棒带电.若不吸引,说明玻璃棒不带电.

②根据电荷间的作用规律判断,方法是:用玻璃棒靠近带电体,若相互排斥,说明玻璃棒带同种电荷;若相互吸引,说明玻璃棒带异种电荷;若没有吸引或排斥现象,说明玻璃棒不带电.

③利用验电器检验,方法是:将玻璃棒与验电器上的金属球接触;若金属箔出现张角,则说明玻璃棒带电;若金属箔没有出现张角,则说明玻璃棒不带电

同类题3

完成表格, 每空一词。

    You must hear about earthquakes, but do you know what to do during and after an earthquake? Here is some advice for you:

Before an earthquake. It is necessary to prepare yourself and your family. All family members should know how to turn off gas, water and electricity and know useful telephone numbers (doctor, hospital, police, 119etc). Never put heavy things over beds.

During the earthquake. It's important for each of you to stay calm. If you are indoors, quickly move to a safe place in the room such as under a strong desk or a strong table. It can protect yourself from falling things. Stay away from windows, large mirrors, heavy things and so on. If you are cooking, turn off the gas.

    If you are outdoors, move to an open area like a playground. It's important to move away from buildings, bridges and trees. If you are driving, stop the car as soon as possible. Stay in your car.

After an earthquake. Once the shaking stops, do not run out of the building at once. It's better to wait and leave when it is safe.

Check around you and help the people in trouble. If your building is badly broken, you should leave it. If you smell or hear gas, get everyone outside and open windows and doors. If you can do it safely, turn off the gas. Report it to the gas company.

Some useful ____ about earthquakes


Before an earthquake

____ yourself and your family.

Don't ____ to turn off gas, water and electricity.

Remember some useful telephone numbers and not to____ heavy things over beds.




____ an earthquake

____ calm is important for each of you.

Moving to a safe place in the room can protect yourself from falling things if you are ____.

Remember to turn off the gas if you are cooking.

Moving to an open area and away from buildings is____ if you are outdoors.

Remember to stop your car and stay in it if you are driving.


After an earthquake

Run out of the building ____ it's safe.

Check around you and help the people in trouble.

Leave your badly broken building.

Keep everyone outside and the windows ____ if you smell or hear a gas.