5. Strength of electric field

Electric field intensity lines of equipotential

Another important element of the electric field is the what is often called the electric field intensity. It is possible to diagrammatically represent the field intensity as equipotential lines on a diagram. These lines can be likened to the contour lines on a map. The equipotential lines are always perpendicular to the electric field.

It is also possible to represent these lines in three dimensions as elliptical spheroids of equal potential.

For a single point charge, the electric field intensity or potential gradient will be highest close to the charge, decaying as it moves further away.

Electric field contours of equipotential
Electric field contours of equipotential around a point charge

In terms of moving along these lines or elliptical spheroids of equal potential, any movement requires no work as a result of movement against the electric field because this movement is always perpendicular to the electric field.

The electric field intensity can be gauged from the closeness of the lines in a similar way to the fact that close contour lines on a map indicate a very steep incline.

Lightning strike represents a large discharge between areas of positive and negative charge where a very high electric field gradient is present
Lightning strike represents a large discharge between positive and negative areas of charge
Photo taken from top of Petronas Towers in Kuala Lumpur Malaysia

When the electric field intensity builds up to a sufficient degree, the dielectric between the negative and positive areas of charge can even lead to a breakdown and current will flow between them giving sparks. Small sparks are relatively commonly seen around the home, but much larger ones occur in the form of lightning.

Electric fields and Coulomb’s law are important in many aspects of electrical and electronics technology. Although the calculations may not be performed that often, a basic knowledge and understanding of the technology is very important. It enables the underlying reasons for some phenomena and elements of items like electronic components to be understood more fully.

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