Electric field strength is a measure of the intensity of an electric field at a specific point. It is defined as the force per unit charge that would be exerted on a test charge placed at that point in the electric field.
Electric field strength is calculated by dividing the force (in Newtons) acting on a test charge by the magnitude of the test charge (in Coulombs). The resulting unit is Newtons per Coulomb (N/C).
The two main factors that affect electric field strength are the magnitude of the source charge and the distance between the source charge and the point in the electric field being measured. The larger the source charge and the closer it is to the point, the stronger the electric field will be.
Electric field strength is a vector quantity, meaning it has both magnitude and direction. The direction of electric field strength is always in the direction that a positive test charge would move when placed in the electric field. This is from positive to negative charges.
Electric field strength and electric potential are closely related. Electric potential is the amount of work needed to move a test charge from one point to another in an electric field. Electric field strength is the force acting on the test charge at a specific point. The relationship between the two is that electric field strength is the negative gradient of electric potential, meaning it is the change in potential over a specific distance. In other words, electric field strength is the driving force that causes a change in electric potential.