Physics Lectures

### Static electricity in our daily life

• tiny spark sound when we take off woolen clothes;
• small shock while getting of car and touch the car door;
• picking tiny pieces of paper with the help of a plastic comb;
• sticking a balloon on a brick wall; etc.

Why do these things happen? it’s static electricity. Before understanding static electricity, it is important to understand the basics of atoms. All objects around us are made of tiny particles called atoms. Atom consists of small particles called electron, proton and neutron. Electrons are negatively charged particles, protons are positively charged particles and neutrons are neutral particles. Therefore, all physical objects are made up of charges.

Opposite charges attract each other while like charges repel. Most of the time negative and positive charges are balanced in an object. Protons and neutrons are held together tightly in nucleus and electrons stay outside the nucleus are held loosely. They can move from one atom to another.

Due to this nature of atomic particles static electricity is the result of an imbalance between negative and positive charges in an object. The rubbing of certain materials against one another can transfer electrons(negative charges). The material which receives an additional electron develops negative charge while the material which loses electron develops a positive charge.

For example, in winter season when we walk, our cloth rub against our body and collect additional electrons. As we take off our cloth we hear tiny spark sound-generate due to discharge of accumulated charge.

Likewise when we get out of car and touch the car door, the negative charge accumulated at the car due to the friction of air gets discharge upon touching it and we feel small shock.

Similarly, when we comb our hair, the plastic comb get some surplus electrons due to friction with hair. This accumulation of negative charge attract tiny pieces of paper.

In order to further investigate this phenomenon, rub a plastic rod on woolen cloth and hang it freely. Bring that woolen cloth near the plastic rod. The rod moves towards the cloth(attraction). Rub a second plastic rod with the woolen cloth and bring it close to the first plastic rod. The hung rod moves away(repel).

We see attraction and repulsion phenomena and conclude that there are two types of static electricity referred as positive charge and negative charge:

• Like charges repel each other
• Unlike charges attract each other
• Static electricity in a result of an imbalance between negative and positive charge in an object.
• Friction between two objects usually lead to this imbalance.
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