The science of static electricity - Anuradha Bhagwat
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And what is it with static electricity and human skin? Human body tissue is composed of 60% or more of water. Human body is a good conductor of electricity! But dry human skin is a different story. Static electric charges can occur when you rub your feet or hand against an insulating material such as wool ro plastic. It is important to remember that static charges, wherever they get accumulated, even on a human skin, lasts only for a short while. If these charges are not zapped off, then they leak off, as nature does not like charge imbalances. For all of us the best practice to avoid a static zap is to touch the Earth, or a wall, or a wooden door, before touching anything metallic.
At home and in factories, there are places where you will see thick metal wires connected physically to Earth – these are known as earthing wires or grounding wires. These earthing wires are important because they do not allow static charges to remain on equipment or even human body.
Why do we experience effects of static electricity mostly in dry, winter climates? Static electricity is more active when the air and materials are dry. This is because moisture and humidity during summer and rainy seasons do not allow static charges to build up. Sparks and lightning can be seen in a volcanic ash cloud also! Why? Besides friction, heat can also cause charge separation within a material. In a volcanic eruption, a large amount of heat is spewing out from the belly of the Earth when hot magma and gas break through the Earth’s crust as ash clouds. This heat may cause charges to separate, and that is why you sometimes see lightning within the ash cloud when a volcano erupts.
For some experiments about static electricity that are simple to do go here! Think you understand and can explain in your own words what is happening when static electricity forms? Give these: “WHAT WILL HAPPEN IF “QUESTIONS a try! Think about each question and then look at the answers below to see the explanation for each one!
WHAT WILL HAPPEN IF?
1. Rub your dry hands together, and then touch a metal surface.
2. Rub your hand on a cat’s fur, and then try and grab a metal spoon.
3. Rub an inflated balloon on your hair, then place the balloon against the wall.
4. You get off a car and touch the door to close it.
5. You jump on a trampoline for a while and then get off it and touch your friend.
Here are your answers:
1. There will not be any charge build up between your dry hands because your palms are made up of the same kind of matter. So when you touch a metal spoon you will not get a static shock. Similarly if you rub a spoon with a metal plate, no static charges will occur.
2. Cat’s fur notoriously is static. Your hands will lose charge. So when you touch a metal spoon, you will experience a static shock.
3. When you rub an inflated balloon on your dry hair the balloon becomes charged negatively. Place the balloon against the wall, and it will stick. This is because the charge on the balloon induces an opposite surface charge on the wall. Closeness wins because the charge on the balloon is slightly closer to the opposite induced charge. After sometime when the charges are neutralized, the balloon will fall off the wall.
4. When you are inside a car remember that the car interiors are mostly made up of man-made insulating materials. You are moving around in the seat, causing charge separation in your body. As long as you are inside the car nothing will happen. If you get off the car and touch a metal door frame quickly, the electrons from the metal will flow in your hand, and you will get a static shock. If you first stand long enough, the charges will flow into the Earth and you may not see the static effect. These days you get anti-static key chains which have electronic circuits that take away the built up charges on your body.
5.Trampoline surface is made up of synthetic material, which as insulators. When you are jumping on it, you will have some charge separation at your feet. When you jump off, and touch a friend, both of you will get a static shock! If you wait a while on the ground, or bend and touch the Earth, and then touch your friend, there will not be any static shock.
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