Electric Field
A charged particle cannot directly interact with another particle kept at a distance. A charge produces something called an electric field in the space around it and this electric field exerts a force on any other charge (except the source charge itself) placed in it.
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Thus, the region surrounding a charge or distribution of charge in which its electrical effects can be observed is called the electric field of the charge or distribution of charge.
Thus, the region surrounding a charge or distribution of charge in which its electrical effects can be observed is called the electric field of the charge or distribution of charge.
The electric field can also be visualised graphically in terms of ‘lines of force’.
Note that all these are functions of position r (x,y,z) . The field propagates through space with the speed of light, c. Thus, if a charge is suddenly moved, the force it exerts on another charge a distance r away does not change until a time r /c later.
Electric Field Strength ( E)
Like its gravitational counterpart, the electric field strength (often called electric field) at a point in an electric field is defined as the electrostatic force Fe per unit positive charge. Thus, if the electrostatic force experienced by a small test charge q0 is Fe, then field strength at that point is defined as
The electric field is a vector quantity and its direction is the same as the direction of the force Fe on a positive test charge.
The SI unit of electric field is N/C.
Here, it should be noted that the test charge q0 should be infinitesimally small so that it does not disturb other charges which produces E.
With the concept of electric field, our description of electric interactions has two parts. First, a given charge distribution acts as a source of electric field. Second, the electric field exerts a force on any charge that is present in this field.
Suppose there is an electric field strength E at some point in an electric field, then the electrostatic force acting on a charge +q is qE in the direction of E, while on the charge – q it is qE in the opposite direction of E.
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Electric Field Lines
Last modified on:3 years agoReading Time:5MinutesElectric Field Lines Electric charges create an electric field in the space surrounding them. It is useful to have a kind of “map” that gives the direction and indicates the strength of the field at various places. Field lines, a concept introduced by Michael Faraday, provide us with an easy way…
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Electric Field of a Line Charge
Last modified on:3 years agoReading Time:3MinutesElectric Field of a Line Charge Positive charge q is distributed uniformly along a line with length 2a, lying along the y-axis between y=–a and y=+a. We are here interested in finding the electric field at point P on the x-axis. Derivation of electric field due to a line charge: Thus,…
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Electric Field Due to a Charged Ring
Last modified on:3 years agoReading Time:4MinutesElectric Field Due to a Charged Ring A conducting ring of radius R has a total charge q uniformly distributed over its circumference. We are interested in finding the electric field at point P that lies on the axis of the ring at a distance x from its centre. We divide…
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Electric Field Due to a Point Charge
Last modified on:3 years agoReading Time:1MinuteElectric Field Due to a Point Charge The electric field produced by a point charge q can be obtained in general terms from Coulomb’s law.First note that the magnitude of the force exerted by the charge q on a test charge q0 is then divide this value by q0 to obtain…
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Conductors and Insulators
Last modified on:4 years agoReading Time:2MinutesConductors and Insulators Solids are mainly classified into two groups, conductors and insulators. In conductors, electric charges are free to move from one place to another, whereas in insulators they are tightly bound to their respective atoms. In an uncharged body, there are equal number of positive and negative charges. The…
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Charging by Rubbing
Last modified on:4 years agoReading Time:3Minutes Charging by Rubbing The simplest way to charge certain bodies is to rub them against each other. When a glass rod is rubbed with a silk cloth, the glass rod acquires some positive charge and the silk cloth acquires negative charge by the same amount. The explanation of appearance of…
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Charging by Contact
Last modified on:4 years agoReading Time:2Minutes Charging by Contact When a negatively charged ebonite rod is rubbed on a metal object, such as a sphere, some of the excess electrons from the rod are transferred to the sphere. Once the electrons are on the metal sphere, where they can move readily, they repel one another and…
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Charging of Insulators
Last modified on:4 years agoReading Time:2Minutes Charging of Insulators Since charge cannot flow through insulators, neither conduction nor induction can be used to charge, insulators, so in order to charge an insulator friction is used. Whenever an insulator is rubbed against a body exchange of electrons takes place between the two. This results in appearance of…
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Can two similarly charged bodies attract each other?
Last modified on:4 years agoReading Time:1Minute Yes, when the charge on one body Q is much greater than that on the other q and they are close enough to each other so that force of attraction between Q and induced charge on the other exceeds the force of repulsion between Q and q. However, two similar…
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If we comb our hair on a dry day and bring the comb near small pieces of paper, the comb attracts the pieces, why?
Last modified on:4 years agoReading Time:2Minutes If we comb our hair on a dry day and bring the comb near small pieces of paper, the comb attracts the pieces, why? Answer: This is an example of frictional electricity and induction. When we comb our hair, it gets positively charged by rubbing. When the comb is brought…
