Electric and Magnetic Fields: Electric Fields

An electric field is a region around a charged object where another charged object experiences a force.
The direction of an electric field is always from positive to negative.
The strength of an electrical field (‘E’) is defined as the force per unit positive charge. It is measured in Newtons per Coulomb (N/C).
The electric field lines point in the direction of the force that a positive test charge would experience if placed in the field.
The principle of superposition describes the resultant force on a test charge due to several static point charges.

Electric fields obey an inverse square law. The strength of an electric field decreases with the square of the distance from the charge creating the field.
Electric fields exist around both stationary and moving charges.
Two fields of the same type (two positive or two negative) repel each other, while two fields of opposite types attract each other.

The equation for the electric field created by a point charge is E = kQ/r², where ‘E’ is the electric field strength, ‘k’ is the Coulomb’s constant, ‘Q’ is the charge, and ‘r’ is the distance from the charge.
The force on a charged object in an electric field is given by F = QE, where ‘F’ is the force, ‘Q’ is the charge of the object, and ‘E’ is the electric field strength.
The work done on a charged particle moving in an electric field is equal to the charge times the change in electric potential or W = QΔV, where ‘W’ is work done, ‘Q’ is charge, and ‘V’ is potential voltage.

A capacitor stores electric charge within an electric field between two conducting plates.
The electric field within capacitors is uniform and the field lines are parallel and equidistant from each other.
The potential difference across a capacitor is directly proportional to the charge stored on it (V = Q/C) where ‘V’ is voltage, ‘Q’ is charge, and ‘C’ is capacitance.

Electric fields are utilized in many everyday applications, including photocopiers, inkjet printers and particle accelerators.
An understanding of electric fields is also vital for designing and working with electronic devices such as capacitors and integrated circuits.