Glossary
Ampere's Law
Relates the magnetic field around a closed loop to the electric current passing through the loop. It is used to calculate magnetic fields generated by steady currents.
Example:
Determining the magnetic field strength inside a long solenoid carrying current involves applying Ampere's Law.
Ampere-Maxwell Law
One of Maxwell's equations, stating that a magnetic field is generated by both an electric current and a changing electric field (displacement current). This correction by Maxwell was crucial for predicting electromagnetic waves.
Example:
During the charging of a capacitor, even though no current flows through the dielectric, a magnetic field is still produced between the plates due to the changing electric field, as explained by the Ampere-Maxwell Law.
Coulomb's Law
Describes the electrostatic force between two point charges. The force is directly proportional to the product of the charges and inversely proportional to the square of the distance between them.
Example:
Calculating the repulsive force between two protons in an atomic nucleus requires applying Coulomb's Law.
Electric Field (E)
A region of space where an electric charge experiences a force. It represents the influence a charge has on its surroundings.
Example:
A charged balloon creates an electric field around it, which can attract small pieces of paper.
Electromagnetic Waves
Oscillating electric and magnetic fields that propagate through space at the speed of light. These waves carry energy and momentum.
Example:
Radio signals, visible light, and X-rays are all forms of electromagnetic waves traveling through the vacuum of space.
Electromagnetism
The fundamental force governing interactions between electrically charged particles, responsible for phenomena like light, electricity, and magnetism.
Example:
When you use a compass, you're observing the effects of electromagnetism as the needle aligns with Earth's magnetic field.
Faraday's Law
States that a changing magnetic field through a surface induces an electromotive force (and thus an electric field) around the boundary of that surface. This principle is crucial for understanding electromagnetic induction.
Example:
A generator works on the principle of Faraday's Law, where rotating coils in a magnetic field induce an electric current.
Faraday's Law of Electromagnetic Induction
One of Maxwell's equations, stating that a changing magnetic field induces an electric field. The negative sign indicates that the induced field opposes the change in magnetic flux (Lenz's Law).
Example:
When you wave a magnet near a coil of wire, the changing magnetic flux through the coil, as described by Faraday's Law of Electromagnetic Induction, generates an electric current.
Gauss's Law
A fundamental law relating the electric flux through a closed surface to the net electric charge enclosed within that surface. It is particularly useful for calculating electric fields in situations with high symmetry.
Example:
To find the electric field produced by a uniformly charged sphere, one would typically use Gauss's Law due to its spherical symmetry.
Gauss's Law for Electric Fields
One of Maxwell's equations, stating that the divergence of the electric field is proportional to the charge density. It implies electric field lines originate from positive charges and terminate on negative charges.
Example:
If you have a cloud of positive charge, Gauss's Law for Electric Fields tells you that electric field lines will spread outwards from it.
Gauss's Law for Magnetic Fields
One of Maxwell's equations, stating that the divergence of the magnetic field is always zero. This implies that magnetic monopoles do not exist, and magnetic field lines always form closed loops.
Example:
No matter how many times you break a bar magnet, you'll always get smaller magnets with both a north and south pole, illustrating Gauss's Law for Magnetic Fields.
Magnetic Field (B)
A region of space where a moving electric charge experiences a force. It is generated by moving charges and permanent magnets.
Example:
The Earth's magnetic field protects us from harmful solar radiation by deflecting charged particles.
Maxwell's Equations
A set of four fundamental equations that unify electricity and magnetism, describing how electric and magnetic fields are generated by charges and currents and how they interact.
Example:
Maxwell's Equations predict the existence of electromagnetic waves, which led to the development of radio communication.