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## Radius of an electron and Distance between electric field lines.

“What is the distance between two lines of force produced by a charge or the distance is zero between them and what is the diameter of electron?” – Ela posted.

The electric field lines are imaginary lines used to represent the electric field visually. The electric field lines are imagined or drawn relatively closer where there is greater electric field. (Though electric flux is often defined as the number of field lines per unit area, it is not so. Electric flux cannot be talked in terms of just numbers. That definition is just to make  a quick idea related to the lines in a given situation. To cross check, just calculate the electric flux from a proton and try to draw that much number of lines around a point)

The radius of electron has been calculated from Mass Energy relation as 2.817 940 3267 x 10-15m

Therefore, Diameter of an electron = 5.635880578916 x 10-15m

Please note that the above value is just a theoretical estimation. The actual size of electron is not experimentally determined.

## From where do electric field lines come towards a negative charge?

Ela posted the question: “ Sir, we know that a negatively charged particle has electric field lines coming radially towards it but what is the origin of these lines?

The electric field lines are just a diagrammatic representation of electric field. The electric field is real but the electric field lines are imaginary. The direction of electric field is also given a conventional definition as “the direction in which a free positive test charge moves in a field.”

Positive and negative are just two kinds of charge. The name “positive” and “negative” are just an arbitrary choice. When a charge is present in space it modifies its surrounding such that another charge kept in its vicinity will experience a force.

If a positive test charge is kept near a negative charge, it will move towards the negative charge. That is why the direction of electric field lines are towards it. Theoretically, electric field lines extend to infinity. (Remember, infinity is also a relative concept. For an amoeba, an ant is infinitely large. For an ant, an elephant is infinitely large and so on.) Just for the sake of it, we can imagine that the lines of force are coming from positive charge(s) at infinity

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