Definition and Properties of Electric Fields
– Electric field is a physical field surrounding charged particles.
– Charged particles exert attractive or repulsive forces on each other.
– Electric field is described by Coulomb’s Law.
– Electric field is stronger near charged objects and weaker further away.
– Electric field originates from electric charges and time-varying electric currents.
– Electric fields hold particles together in atoms and molecules.
– Electric field is defined as a vector field.
– The SI unit for electric field is volt per meter (V/m).
– Electric field is a fundamental force of nature.
– Electric field can be visualized using lines of force.
– Electric field lines originate from positive charges and terminate at negative charges.
– Electric field lines never cross or close in on themselves.
– Field lines represent the density of the electric field.
– Study of electric fields created by stationary charges is called electrostatics.
– Electric fields are caused by electric charges and time-varying magnetic fields.
– Gausss law and Faradays law describe the behavior of electric fields.
– Electric and magnetic fields are described by Maxwells equations.
– Electric field is inversely proportional to the square of the distance from the charge.
– Coulomb force on a charge is equal to the product of the charge and electric field.
– Electric fields satisfy the superposition principle.
– Total electric field at a point is the vector sum of the electric fields due to individual charges.
– Electric potential difference between two points is called voltage.
– Electric field cannot be described independently of the magnetic field.
– Electric potential can be defined using the magnetic vector potential.
Continuous vs. discrete charge representation
– Electromagnetism equations are best described in a continuous description.
– Charges can be described as discrete points.
– Some models describe electrons as point sources with infinite charge density.
– Charge can be mathematically described as charge density.
– Charge distribution can be approximated by many small point charges.
Electrostatic fields
– Electrostatic fields do not change with time.
– Coulomb’s law fully describes electrostatic fields.
– Electrostatic fields are present when charged matter is stationary.
– Electric currents that are unchanging also produce electrostatic fields.
– Electric fields surround positive and negative charges.
Parallels between electrostatic and gravitational fields
– Coulomb’s law describes the interaction of electric charges.
– Newton’s law of universal gravitation describes gravitational interaction.
– Electric field E and gravitational field g have similarities.
– Electrostatic and gravitational forces are central, conservative, and obey an inverse-square law.
– Mass is sometimes referred to as gravitational charge.
Uniform fields
– Uniform fields have a constant electric field at every point.
– Uniform fields can be approximated by parallel conducting plates with a voltage difference.
– Electric field magnitude in a uniform field is given by ΔV/d.
– Positive charges repel and experience a force away from positively charged plates.
– Electric field magnitude in micro and nano-applications is in the order of 10 V⋅m.
Note: The remaining content was not provided. Source: https://en.wikipedia.org/wiki/Electric_field
An electric field (sometimes E-field) is the physical field that surrounds electrically charged particles. Charged particles exert attractive forces on each other when their charges are opposite, and repulsion forces on each other when their charges are the same. Because these forces are exerted mutually, 2 charges must be present for the forces to take place. The electric field of a single charge (or group of charges) describes their capacity to exert such forces on another charged object. These forces are described by Coulomb's Law, which says that the greater the magnitude of the charges, the greater the force, and the greater the distance between them, the weaker the force. Thus, we may informally say that the greater the charge of an object, the stronger its electric field. Similarly, the electric field is stronger nearer charged objects and weaker further away. Electric fields originate from electric charges and time-varying electric currents. Electric fields and magnetic fields are both manifestations of the electromagnetic field, one of the four fundamental forces of nature.
| Electric field | |
|---|---|
 Effects of an electric field. The girl is touching an electrostatic generator, which charges her body with a high voltage. Her hair, which is charged with the same polarity, is repelled by the electric field of her head and stands out from her head. | |
Common symbols | E |
| SI unit | volt per meter (V/m) |
| In SI base units | m⋅kg⋅s−3⋅A−1 |
Electric fields are important in many areas of physics, and are exploited in electrical technology. In atomic physics and chemistry, for instance, the interaction in the electric field between the atomic nucleus and electrons is the force that holds these particles together in atoms. Similarly, the interaction in the electric field between atoms is the force responsible for chemical bonding that result in molecules.
The electric field is defined as a vector field that associates to each point in space the electrostatic (Coulomb) force per unit of charge exerted on an infinitesimal positive test charge at rest at that point. The derived SI unit for the electric field is the volt per meter (V/m), which is equal to the newton per coulomb (N/C).
