Electric Charges and Fields

Have you ever heard a crackle or witnessed a spark while removing synthetic clothing like a sweater in dry weather? How about some background information on this phenomenon? Lightning, which we see in the sky during thunderstorms, is another electric charge and field form. 

All of these experiences are the consequence of electric charges being discharged through your body due to rubbing insulating objects. It can also be caused by the build-up of static electricity. 

Electric charge

The word “electricity” comes from the Greek word Elektron, which means “amber.” The magnetic and electric forces present in materials, atoms, and molecules affect their properties. The term “electric charge” refers to just two types of entities.

When a matter is exposed to an electromagnetic field, it develops an electric charge, which results in a force. Don’t forget the fact that the electric field on the equatorial line of an electric dipole. 

For those who don’t know, a body can also be charged by induction, conduction, and friction. Also, a body with a negative charge states that it is infused with surplus electrons. On the contrary, a body with inadequate electrons states that it has a positive charge. 

What are the basic properties of electric charges? 

Here are the basic properties of electric charge:

Additivity of charges

If a system has two-point charges, q1 and q2, the total charge of the system may be considered by adding both the terms, i.e., charges add up like the mass of the body.

The charge is conserved

When two bodies are rubbed together, the charge obtained by one body is similar to the charge lost by the other. Charges may be redistributed in an isolated system with numerous charged bodies due to interactions among the bodies, but the isolated system’s overall charge is always retained.

Quantization of charge

One of the basic properties of electric charges is that all free charges are fundamental multiples of a basic unit of charge identified by e, according to experiments. 

Take note that the charge’s basic unit is the charge carried by protons or electrons. 

Electric field

The space around any charge in which its effect may be felt by other charges is referred to as the electric field.

Electric field lines

“An electric field line is an imaginary line or curve traced through a region of space, with its tangent in the direction of the electric field vector at any location.” The relative closeness of the lines at a given spot indicates the intensity of the electric field there.”

Electric field due to dipole

Let a pair of equal or opposite charges Q and -Q be separated by a distance of 2x. The dipole moment vector (let’s assume it as p) is equal to 2Qx and is in the direction from -Q to Q. 

Physical significance of dipoles

In CO2 and CH4 types of molecules, the dipole moment is zero but there’s a development of dipole when an electric field on the equatorial line of an electric dipole. Talk about other molecules, where the centres of negative charges and positive charges do not have an eternal electric dipole moment. Those show at a point on the axis of an electric dipole even in the absence of an electric field called polar molecules. An example of a polar molecule is Water molecules, H2O. 

When the dipole is short and 2a << r, the formula becomes

Dipole in a uniform external field

There is a force at work. E is uniform because the net dipole is zero. Remember that a given charge is situated at a certain distance from an electric dipole. 

A torque is formed on the dipole when the charges are separated, and the forces operate at various places. The torque (couple) is independent of the origin when the net force is zero. The magnitude is calculated by multiplying the magnitude of each force by the couple’s arm (perpendicular distance between the two antiparallel forces).

Electric field due to line charge

The electric field owing to line charge can be easily found using Gauss’ law. A tiny loaded rod with a uniform charge density can be thought of as a line charge.

Assume a right circular closed cylinder with radius r and length l with an infinitely long line of charge as its axis to find electric intensity at point P at a perpendicular distance r from the rod. Since all locations on the curved surface of the Gaussian surface are at the same distance from the line charge, the magnitude of the electric field strength at each point is the same.

Electric field due to ring

The ring field can also be utilised as an element in calculating the electric field of a charged disc.

The field at point P on the ring’s axis is determined. The total field is the superposition of all such fields due to all charge elements surrounding the ring, and the field dE as a charge element dq is represented. While the perpendicular fields add up to zero, the field’s differential x-component is

Conclusion 

In the above article we learned about the electric charge and field. The space around any charge in which its effect may be felt by other charges is referred to as the electric field. An electric field line is an imaginary line or curve traced through a region of space, with its tangent in the direction of the electric field vector at any location. Electric field due to dipole and ring also explained in the article.