Online CBSE Class 8 Science Chapter 14 – Some Natural Phenomena
We will discuss the Class 8 Science chapter 14 Some Natural Phenomena in this article. We see many natural phenomena around us like rain, storm, volcanic eruptions, cyclones, etc. Out of them, some are harmful and some are harmless to us. Lightning occurs because of the transfer of massive electric charges. Natural disasters sometimes cause tremendous damage to life and property.
Let’s discuss electric charges first.
All matter is made up of atoms. Every atom is made up of positively charges particles, negatively charges particles and neutral particles. The positively charged particles of an atom are called protons. The negatively charged particles are called electrons.
The atom as a whole consists of an equal number of positive and negative charges and it is called electrically neutral.
If the charge is not balanced, the atom will have a positive charge if protons are more in number than electrons and negative charge if electrons are more in number than protons.
Objects with the same type of charge brought together will repel each other. Objects with opposite charge will attract each other.
From above we can conclude easily that like charges repel each other and unlike charges attract each other.
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Charging an object
An object can be given an electric charge by using the below-mentioned methods.
- Charging by induction-Charging is done without the charged body touching the object that has to be charged.
Eg: -A charged glass rod is brought close to a metal object but does not touch it.
- Charging by friction –This kind of charging is done by rubbing one material with another.
Eg:-Rubbing glass with silk
- Charging by the conduction-An object can also be charged by making it touch a charged body. The nature of the charge acquired will be the same as that of the charging body.
Eg:-If we take a charged glass rod and touch a metal object with it, the metal object will also become charged.
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Transfer of charge
Electric charge can be transferred from a charged object to another through a metal conductor. An electroscope is a device that works to detect and measure electric charge. It consists of two very thin metal strips connected to a metal knob by a metal rod.
Working of electroscope
- A charged object is made to touch the knob of the electroscope.
- The charge is transferred to the thin metal strips through the metal rod.
- The metal strips repel each other as they have similar charged and separate from each other.
Discharging is a process when a charged object comes in contact with a body which is not charged, electric charges jump from the charged body to the uncharged body till the charges on both sides become equal.
Earthing is a process when a body comes in contact with the earth, directly or indirectly then the charges are discharged to the earth.
We will discuss the lighting process in the next article of Class 8 Science.
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