The electric field equation is shown below. Before we get to it, ask yourself this question, " What is an electric field? "
However, notice that the test charge did not actually touch the charged object.
Therefore, many people may ask themselves this question, " How does the
charged object know that the test charge is in the neighborhood? "
We answer this question by saying that there is a force field, more specifically, an electric field in the space surrounding the charged object.
The electric field is however a vector field with more than one vector.
Use one vector for each charge around the charged object and an electric field will look like the graph you see below.
The electric field equation measures the force exerted on just 1 small test charge placed in the field.
Important observation about the first illustration above.
Action at a distance can be mindboggling and this has even troubled Isaac Newton and many others physicists.
Nonetheless, when we think about it deep enough, we will see that
action at a distance can happen with iron filings and a magnet.
It is also happening with objects placed near the earth in space. These objects will be in a gravitational field as they each experience the force of gravity.
The gravitational field around the earth is what keep a satellite in its orbit near the earth.
We can find another equation for the electric field by combining the following 2 equations.
E =
F
q_{1}

F = k
qq_{1}
d^{2}

Notice that since q_{1} is positive as already stated earlier, q_{1} = q
An electric field quiz to test your understanding of electric field. You will not need to use a paper and pencil to complete this quiz.
First, read this lesson about electric field and then take this quiz.
Objective of the quiz:
Test your knowledge with the quiz below: 