Source electric interaction.
Charge is conserved and appears with positive or negative sign.
Side 154
Electromagnetism
Electric and magnetic phenomena unified as interacting fields generated by charge and current, capable of storing energy, exerting force and propagating as waves.
charge→field→potential→induction→wave
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16working concepts
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SS-1.0standard
Charge creates electric fields that act on other charges.
Fields replace direct action at a distance with a local description defined throughout space.
Describe force from stationary point charges.
The inverse-square structure produces strong local influence that weakens with distance.
Add fields from multiple sources.
Linearity lets complex configurations be decomposed into simpler contributions.
Relate enclosed charge to electric flux.
Symmetry can turn difficult field calculations into simple flux arguments.
Potential reframes electric force in terms of energy.
Scalar potential often simplifies electrostatic reasoning when fields are conservative.
Assign configuration-dependent energy.
Work done by electric forces changes electric potential energy.
Measure potential difference per unit charge.
Voltage describes energy change available to charges moving between locations.
Identify surfaces of constant potential.
Electric fields cross equipotential surfaces perpendicularly.
Store separated charge and field energy.
Geometry and dielectric environment determine how much charge is stored for a given voltage.
Currents create magnetic fields and changing flux creates electric effects.
Motion and change connect the electric and magnetic sectors.
Move charge through a region.
Current density connects charge motion to magnetic-field generation.
Combine electric and magnetic force on charge.
Magnetic force changes direction of motion without directly doing work on a point charge.
Generate electromotive force from changing magnetic flux.
Induction underlies generators, transformers and many sensors.
Set the direction of induced response.
Induced currents oppose the change in flux that produced them.
Maxwell's equations make fields dynamical.
The complete field equations predict self-propagating electromagnetic waves.
Link magnetic circulation to current and changing electric field.
The displacement-current term completes the symmetry needed for wave propagation.
Combine field laws into propagating solutions.
Electric and magnetic disturbances travel through space at a characteristic speed.
Track energy through the Poynting vector.
Electromagnetic energy can move through empty space independently of material charge transport.
Vary wave frequency across one electromagnetic family.
Radio, visible light and X-rays differ primarily in frequency and interaction scale, not in underlying field type.
Electricity and magnetism are one field theory. Changing electric and magnetic fields generate one another, and Maxwell's equations compress the relationship into a single dynamical system.