Electric Field

When people think of forces, they usually think about forces like friction, normal force, and forces you can apply to an object through physical exertion. However, these forces are all contact forces and as shown by forces like gravity and electric forces, it's quite clear that these aren't initiated through contact. These types of forces are visualized with map-like planes known as vector fields. These fields essentially act like webs around given sources(gravitational fields surround point masses and electric fields surround electrically charged objects). The closer you are to the source, the greater the field is around you; the farther you are from the source, the lesser the field is around you.

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Electric point charges create electric fields around them, which map out how the charge interacts with other objects. You can also better express the electric field as the amount of force a test charge of 1 C would experience from the source charge. In other words, if I took a charge of 1 C and placed it in the electric field of another source charge, the electric field is how much force that 1 C charge would experience.

This basically states that the electric field on a given point charge is the electric force per charge on a given object. This means that the charge of the object that's test charge doesn't play a role in the electric field at the point where the object is. If you disregard the signs of the quantities, you can manipulate the expression in terms of electric force.

It is worth noting that the electric field of an object will be affected by magnetic forces if the field is moving in space.

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Now, since we've quantified the electric field that an object can create in the space around it, there are some general rules that are useful for conceptualizing electric fields.

Positive source charges create electric field lines that are directed radially outward from themselves. Negative source charges create electric field lines that are directed radially inward to themselves. If you take another test charge and put it in the electric field of a source charge, if the test charge and the source charge have equal sign charges, the test charge will experience an electric force in the direction of the electric field of the source charge. If the test charge and source charge have opposite signed charges, the test charge will experience an electric force opposite the direction of the electric field of the source charge. Knowing these conceptual shortcuts will allow you to make some simplifying steps when analyzing charges and their given electric fields and forces on each other.

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Another important idea about electric fields is that if you have multiple electric fields on a test charge, the total electric field on the test charge is the vector sum of the individual electric fields given by the individual source charges.