Simple Electrostatic Phenomenon From Our Daily Life
Charging of a plastic comb after combing
Examples of conductors and insulators
Examples of conductors are metals(silver, copper and aluminium, etc), mercury, earth, etc.
Examples of insulators are non-metals (plastic, glass, pure water, sulphur, etc). Some exceptions that are non-metals but not insulators are graphite and tap water.
Examples of insulators are non-metals (plastic, glass, pure water, sulphur, etc). Some exceptions that are non-metals but not insulators are graphite and tap water.
Earthing and its advantages
Connecting a charged object to the earth with the help of conducting wires or physical contact is called Earthing. The earth is considered to be a huge reservoir of electrons. Depending upon the charge on the object, the earth provides or accepts electrons from a charged object connected to it.
Interaction of Charges
Charge is a fundamental property of matter. It is of two kinds: positive and negative. The smallest charge is that of an electron. It is negative and its value is . In a material, only electrons are free to move.
Interaction of charges is explained as:
1. Like charges repel.
2. Unlike charges attract.
Interaction of charges is explained as:
1. Like charges repel.
2. Unlike charges attract.
Introduction to Charged and Uncharged Bodies
Charged Body :
A body which possess charge is called charged body. But this charge may be either positive or negative.
Depending upon the nature of charge, a charged body may be classified as follow :
A body which is electrically neutral is called as an uncharged body. They have equal negative and positive charge. As a result, they remain neutral.
A body which possess charge is called charged body. But this charge may be either positive or negative.
Depending upon the nature of charge, a charged body may be classified as follow :
- Positively Charged Body : A body with more number of proton is known as positively charged body.
- Negatively Charged Body : A body with more number of electrons is known as negatively charged body
A body which is electrically neutral is called as an uncharged body. They have equal negative and positive charge. As a result, they remain neutral.
Basic properties of electric charges
- Additivity of electric charges: The total charge of the system can be obtained by algebraically adding the charges.
- Conservation of charge: The total charge of an isolated system is always conserved.
- Quantisation of charge: Electric charge is always an integral multiple of e where
Construction and Working of Gold Leaf Electroscope
Gold Leaf Electroscope :
It is a simple device to detect the presence of charge on any body.
Construction : It consists of a metal rod which is fitted in an insulating box. Metal rod has a metal knob at its top. Two gold leaves are also attached at the bottom end of the rod.
Working :Since electroscope is used to detect the presence of charge. So through it we can find whether a body is charged or uncharged.
Therefore the body to be detected is brought close enough to the metal knob. When a charged object touches the knob at the top of the rod, charge flows through the rod on to the leaves.
Both the gold leaves will have same charge and hence as a result they will repel and diverge.
The degree of divergence is an indicator of the amount of charge i.e., more the charge, more will be the divergence.
It is a simple device to detect the presence of charge on any body.
Construction : It consists of a metal rod which is fitted in an insulating box. Metal rod has a metal knob at its top. Two gold leaves are also attached at the bottom end of the rod.
Working :Since electroscope is used to detect the presence of charge. So through it we can find whether a body is charged or uncharged.
Therefore the body to be detected is brought close enough to the metal knob. When a charged object touches the knob at the top of the rod, charge flows through the rod on to the leaves.
Both the gold leaves will have same charge and hence as a result they will repel and diverge.
The degree of divergence is an indicator of the amount of charge i.e., more the charge, more will be the divergence.
Gold leaf electroscope
GIF
Gold leaf electroscope has two gold leafs suspended from a metal(usually brass) stem in a vacuumed glass jar and connected to a metal cap. The glass is grounded with the help of a metal foil to make it uncharged. It can be used to:
- Detect charge: Body under test is touched with the metal cap. If the leaves diverge, the body is charged and if there is no effect on leaves, then the body is uncharged.
- To identify the nature of charge: The electroscope is charged by a known body(say positively charged body) and then the body is removed. Next, the body under test is brought in contact with the metal cap. If the leaves diverge further, the body has same charge(positive) and if the leaves come closer to each other, the body has opposite charge(negative).
- Identify a body as conductor or insulator: Take two electroscopes. Charge one of the electroscopes so that its leaves will diverge. Then, connect the two electroscopes by the object under test. If the leaves of other electroscope diverge, the body is a conductor and if there is no effect on the electroscopes, the body is an insulator.
Applications of Gold Leaf Electroscope
These are some of the applications of Gold Leaf Electroscope :
1.Detect charge :
Body under test is touched with the metal cap. If the leaves diverge, the body is charged and if there is no effect on leaves, then the body is uncharged.
2.To identify the nature of charge :
The electroscope is charged by a known body(say positively charged body) and then the body is removed. Next, the body under test is brought in contact with the metal cap. If the leaves diverge further, the body has same charge(positive) and if the leaves come closer to each other, the body has opposite charge(negative).
3.Identify a body as conductor or insulator :
Take two electroscopes. Charge one of the electroscopes so that its leaves will diverge. Then, connect the two electroscopes by the object under test. If the leaves of other electroscope diverge, the body is a conductor and if there is no effect on the electroscopes, the body is an insulator.
1.Detect charge :
Body under test is touched with the metal cap. If the leaves diverge, the body is charged and if there is no effect on leaves, then the body is uncharged.
2.To identify the nature of charge :
The electroscope is charged by a known body(say positively charged body) and then the body is removed. Next, the body under test is brought in contact with the metal cap. If the leaves diverge further, the body has same charge(positive) and if the leaves come closer to each other, the body has opposite charge(negative).
3.Identify a body as conductor or insulator :
Take two electroscopes. Charge one of the electroscopes so that its leaves will diverge. Then, connect the two electroscopes by the object under test. If the leaves of other electroscope diverge, the body is a conductor and if there is no effect on the electroscopes, the body is an insulator.
Electrostatic Induction
When an uncharged object is placed very close to a charged conductor without touching, the nearer end acquires a charge opposite to the charge on the charged conductors and the two bodies attract. This is called charging by induction. The net charge on the bodies remains the same and body is charged until they are kept close or brought in contact.
Charging by friction
By using the method of friction, positive charge is developed on one of the bodies and negative charge on the other. When these two bodies are brought close, they attract.
Some objects have tendency to gain positive charge (example glass and ebonite rod) while some objects have the tendency to gain negative charge(example silk).
Some objects have tendency to gain positive charge (example glass and ebonite rod) while some objects have the tendency to gain negative charge(example silk).
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