Introduction To Electrostatics : The branch of physics which deals with the study of charges at rest is called electrostatics.
If a glass rod is rubbed with silk cloth, electrons pass from glass rod to silk cloth and the glass rod becomes positively charged while the silk piece attains an equal negative charge. Since glass rod and silk cloth are both insulators, they retain charges on them because electrons cannot move.
In other words, electricity on them is static or at rest and hence the process comes under the Electrostatics.
Explanation of Charges : The number of electrons in an atom is equal to the number of protons, therefore, atom is neutral as whole. A body consists of atoms, therefore, the body is neutral under ordinary conditions.
However, if from such a neutral body, electrons are detached (by rubbing etc.), there occurs a deficit of electrons in the body. Consequently the body no longer remains neutral due to the shortage of electrons. The result is that the body attains positive charge.
When a body is short of its due share of electrons or there is deficit of electrons in the body it is said to be positively charged.
On the other hand, a negatively charged body has excess of electrons from its normal due share. If a neutral body is supplied with electron, the body loses its neutrality and attains a negative charge.
Therefore, a negatively charged body has excess of electrons from its normal due share.
Total deficiency or excess of electrons in a body is known as charge.
To give a negative charge to any body, extra electrons must be supplied to it. To supply these extra electrons, work will have to be done, which is stored in the body in the form of energy. This makes the charged body capable of doing work.
Units of Charge : The charge on an electron is so small that it is not possible and convenient to take it as the unit. In practice, the charge is measured in coulomb (C). One coulomb of charge is equal to the charge on 625 × 1016 electrons. i.e.
Charge of 1 coulomb = charge on 625 × 1016 electrons.
∴ Practical unit of charge is coulomb. And a smaller unit of charge is micro-coulomb is also used.
1 micro-coulomb (i.e. 1 µC) = 10−6 C coulomb.
If a glass rod is rubbed with silk cloth, electrons pass from glass rod to silk cloth and the glass rod becomes positively charged while the silk piece attains an equal negative charge. Since glass rod and silk cloth are both insulators, they retain charges on them because electrons cannot move.
In other words, electricity on them is static or at rest and hence the process comes under the Electrostatics.
Explanation of Charges : The number of electrons in an atom is equal to the number of protons, therefore, atom is neutral as whole. A body consists of atoms, therefore, the body is neutral under ordinary conditions.
However, if from such a neutral body, electrons are detached (by rubbing etc.), there occurs a deficit of electrons in the body. Consequently the body no longer remains neutral due to the shortage of electrons. The result is that the body attains positive charge.
When a body is short of its due share of electrons or there is deficit of electrons in the body it is said to be positively charged.
On the other hand, a negatively charged body has excess of electrons from its normal due share. If a neutral body is supplied with electron, the body loses its neutrality and attains a negative charge.
Therefore, a negatively charged body has excess of electrons from its normal due share.
Total deficiency or excess of electrons in a body is known as charge.
To give a negative charge to any body, extra electrons must be supplied to it. To supply these extra electrons, work will have to be done, which is stored in the body in the form of energy. This makes the charged body capable of doing work.
Units of Charge : The charge on an electron is so small that it is not possible and convenient to take it as the unit. In practice, the charge is measured in coulomb (C). One coulomb of charge is equal to the charge on 625 × 1016 electrons. i.e.
Charge of 1 coulomb = charge on 625 × 1016 electrons.
∴ Practical unit of charge is coulomb. And a smaller unit of charge is micro-coulomb is also used.
1 micro-coulomb (i.e. 1 µC) = 10−6 C coulomb.
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