Wednesday, May 22

Static Electricity Materials

Static Electricity

Static electricity is the accumulation of excess charge on the surface of an insulator, that is, a material that does not conduct electricity.

Why does the charge accumulate?

An atom is made of a positively charged nucleus (made of protons and neutrons) surrounded by several shells of electrons which are negatively charged. Objects that we see everyday are made of electrically neutral atoms or molecules. This means that the number of positive charges and negative charges are equal. However, when two electrically neutral materials are in contact, the electrons may move from one material to another. This means that one material gets an excess of negative charge, while the other one gets an excess of positive charge. If you separate the materials after the electrons have moved, there will be a charge imbalance in the materials.

In a conducting material, the charges are immediately conducted away, and the charge does not accumulate. So, the phenomenon of static charge accumulation or static electricity can be seen only in insulators or non-conductors.

Experiments of static electricity materials:

You can see how static charges accumulate by doing these simple experiments.

Experiment 1:

Rub a balloon vigorously on a sweater.  The rubbing motion increases the area of contact between the two surfaces, making it easier for charges to migrate. The balloon gets negatively charged and the jumper aquires a positive charge. Now, if you bring the balloon close to your hair, your hair will cling to the balloon. This is known as static cling.

Experiment 2:

Use a plastic comb to comb through your hair about ten times. Now, turn on a tap so that you have a steady water flow. The flow should not be very fast. If you bring the comb near the stream of water without touching it, the water will bend towards the comb. This is because the charges on the comb pull on the uncharged water.

Removing static electricity:

Static electricity can be removed by bringing the material into contact with a conductor, or with a region that has an excess charge that is opposite to the material. This causes the charge to neutralize, resulting in a static 'shock.' In regions of high humidity, the air itself will conduct away the static charges.

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