Hello, welcome to my instructable. Today we will learn about static electricity, make an electroscope and about capacitors. So, let's start.
What is Static electricity?
Static electricity can be defined as the electricity that belongs to non-metals. Why? more on that later. First, let's understand what is it?
When you rub a plastic pen or ruler on dry hair and bring it near pieces of paper, what happens? The paper sticks to the plastic pen or ruler. Well, that's basically due to static electricity.
If the electric charge produced in an object remains at the same place in it, it is static electricity. The common example of static electricity is Lightning.
Why does this happen?
Normally, atoms are electrically neutral, that is the number of protons and electrons are equal. When certain bodies are rubbed against one another, electron transfer takes place, and the electron is transferred from one body to another. The body who loses the electron gains positive charge and who receives the electron gains a negative charge.
Please note: Only a compatible pair of bodies have the ability to attract other bodies. Metals cannot be charged through friction since metals are good conductors of electricity, the charge is spread immediately to other parts. So, static electricity is not formed on metals.
Properties of Electric charges:
- Charged body attracts uncharged bodies
- Unlike charges attract each other
- Like charges repel each other
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Step 1: Let's Make an Electroscope
Before we create it, there is one important question left: How do we know whether a body is charged or not?
If 2 bodies attract each other we cannot say with certainty that both of them possess charge. But if bodies repel each other, it is sure that both the bodies possess like charges. So repulsion, and not attraction, is the means by which we confirm whether bodies possess charge or not. By using this idea let's build an electroscope. An electroscope is an instrument to know the presence of a static charge. So, let start.
- A copper wire
- Aluminum foil
- One transparent plastic bottle
Method of construction:
Take the lid of the bottle and make a hole at the center. Fix the straw by inserting some portion of it through the hole. Pass the copper wire through the straw. Bend both ends of the wire. Hook 2 aluminum foils pieces of the same size. And close the lid. Viola! The Electroscope is ready. You may think this is quite easy. Yes! it's right, it's quite fun to build.
Step 2: Let's Do Some Experiments
Fun fact: Volcano eruptions can trigger lightning.
If an electroscope is charged, after a while the leaves come close to each other. How can we retain charge for a time? Let's do an experiment.
(See the diagrams above to understand more)
a) A negatively charged rod is brought near an electroscope
b) On the leaves of the electroscope, negatively charged is formed, and a positive charge is formed at the top
c) When the earthing is done, only the charge on the lost
d) Earthing is removed
e) When the charged rod is removed, charge spreads everywhere in the electroscope and the leaves remain separated
Thus, the charge could be retained for a long time. Note that we have charged the electroscope positively. To charge it negatively just bring a positively charged rod and follow the same process.
(See the last diagram above to understand more)
Cut the bottom of the bottle and place an aluminum foil inside the bottle. And charge the electroscope we can see the leaves retain their charge for a long time. When a conductor is placed near a charged body, the opposite charge would be induced on the surface of the conductor facing the charged body. The charge on the electroscope stays for a long time due to the attraction of these opposite charges. A Capacitor is constructed on the basis of this principle.
Step 3: Capacitors
The device which can store electric charge is called a capacitor. In order to increase the ability to store electricity in a capacitor with plates of fixed area, suitable insulators are used between the plates. such insulators are called dielectric. Paper, polyester, air,... can be used as dielectrics. Capacitors are usually known by the dielectrics used in them. The ability of a capacitor to store charge is known as capacitance and its unit is farad (F).
Step 4: Sorry!
Sorry friends a video is currently not available. That is because I don't have the right gears to shoot a video. But in future I'm sure I will post a video and release an improved version electroscope. Thank you for reading my instructable and see you next time...