Electrical work
Encyclopedia
Electrical work is the work done on a charged particle by an electric field
. This energy is similar to mechanical work
in that the equation for electrical work is of the same form:
where
The electric field is essentially the force
per unit charge
, and hence by multiplying the charge by the separation between positive and negative regions of field, the work per unit charge is obtained.
It requires positive external work to move a positive charge into a region possessing a higher value of voltage
. This is because external work is needed to be done against the field
of the electric force. Similarly, it requires positive external work to transfer a negatively charged particle from a region of higher voltage to a region of lower voltage.
Under normal circumstances, positively charged particles that are free to move will always tend to shift towards the direction of lower voltages. In contrast to this behavior of positive charges, particles that are negatively charged tend to shift towards regions that possess lower voltage.
The electric work which is done by an electric field is independent of the path
followed by the carriers of charge. There is no change in the voltage around any closed path; this fact is brought out by the observation that when returning to the starting point in a closed path, the net of the external work done is zero. The same phenomenon holds good for electric fields as well.
The fact explained above forms the basis of one of the most fundamental laws governing electrical and electronic circuits, the Kirchoff's voltage law. According to this principle, the voltage gains and the drops that occur around any electrical circuit loop is always equal to zero.
Electric field
In physics, an electric field surrounds electrically charged particles and time-varying magnetic fields. The electric field depicts the force exerted on other electrically charged objects by the electrically charged particle the field is surrounding...
. This energy is similar to mechanical work
Mechanical work
In physics, work is a scalar quantity that can be described as the product of a force times the distance through which it acts, and it is called the work of the force. Only the component of a force in the direction of the movement of its point of application does work...
in that the equation for electrical work is of the same form:
where
- q is the chargeElectric chargeElectric charge is a physical property of matter that causes it to experience a force when near other electrically charged matter. Electric charge comes in two types, called positive and negative. Two positively charged substances, or objects, experience a mutual repulsive force, as do two...
of the particle - E is the strength of the electric fieldElectric fieldIn physics, an electric field surrounds electrically charged particles and time-varying magnetic fields. The electric field depicts the force exerted on other electrically charged objects by the electrically charged particle the field is surrounding...
- r is the distance
The electric field is essentially the force
Force
In physics, a force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape. In other words, a force is that which can cause an object with mass to change its velocity , i.e., to accelerate, or which can cause a flexible object to deform...
per unit charge
Electric charge
Electric charge is a physical property of matter that causes it to experience a force when near other electrically charged matter. Electric charge comes in two types, called positive and negative. Two positively charged substances, or objects, experience a mutual repulsive force, as do two...
, and hence by multiplying the charge by the separation between positive and negative regions of field, the work per unit charge is obtained.
It requires positive external work to move a positive charge into a region possessing a higher value of voltage
Volt
The volt is the SI derived unit for electric potential, electric potential difference, and electromotive force. The volt is named in honor of the Italian physicist Alessandro Volta , who invented the voltaic pile, possibly the first chemical battery.- Definition :A single volt is defined as the...
. This is because external work is needed to be done against the field
Electric field
In physics, an electric field surrounds electrically charged particles and time-varying magnetic fields. The electric field depicts the force exerted on other electrically charged objects by the electrically charged particle the field is surrounding...
of the electric force. Similarly, it requires positive external work to transfer a negatively charged particle from a region of higher voltage to a region of lower voltage.
Under normal circumstances, positively charged particles that are free to move will always tend to shift towards the direction of lower voltages. In contrast to this behavior of positive charges, particles that are negatively charged tend to shift towards regions that possess lower voltage.
The electric work which is done by an electric field is independent of the path
Path (topology)
In mathematics, a path in a topological space X is a continuous map f from the unit interval I = [0,1] to XThe initial point of the path is f and the terminal point is f. One often speaks of a "path from x to y" where x and y are the initial and terminal points of the path...
followed by the carriers of charge. There is no change in the voltage around any closed path; this fact is brought out by the observation that when returning to the starting point in a closed path, the net of the external work done is zero. The same phenomenon holds good for electric fields as well.
The fact explained above forms the basis of one of the most fundamental laws governing electrical and electronic circuits, the Kirchoff's voltage law. According to this principle, the voltage gains and the drops that occur around any electrical circuit loop is always equal to zero.