Electric Fields and Forces - QuickCheck Vocabulary (Chapter 20)

Vocabulary flashcards covering key concepts from the QuickCheck questions on Electric Fields and Forces.

Electric field

A region around a charged object where another charge experiences a force; described by the field vector E and related to force by F = qE.

Field lines

Imaginary lines that show the direction of the electric field; denser lines indicate a stronger field and lines exit from positive charges and enter negative charges.

Charge (positive/negative)

A property of matter that produces electric forces; like charges repel, opposite charges attract; positive and negative denote the two signs of electric charge.

Conductor

A material in which electric charges move freely; in electrostatic situations, excess charge resides on the surface.

Insulator

A material in which charges do not move freely; charges remain localized and do not readily move through the material.

Polarization

Distortion of charge distribution inside a material in an external electric field, producing a dipole moment without a net external charge (common in dielectrics).

Charging by induction

Charging an object without direct contact by bringing a charged object near it, causing redistribution of charges; can leave a net charge after separation or grounding.

Charging by conduction

Charging by direct contact between objects, allowing charge to transfer until they share the total charge.

Net charge

The total amount of electric charge on an object; can be positive, negative, or zero.

Grounding

Connecting to Earth to allow charges to flow to or from the ground, often used during induction to control final net charge.

Induced charges

Charges that rearrange on a conductor in response to an external electric field, creating regions of charge separation.

Dipole

A pair of equal and opposite charges separated by a distance, forming a dipole moment.

Dipole moment

p = qd, the product of the magnitude of the charge and the separation distance between the charges.

Torque on a dipole in a uniform electric field

A torque τ = pE sinθ that tends to rotate the dipole to align with the field; in a uniform field, there may be no net translational force.

Uniform electric field

An electric field with constant magnitude and direction throughout the region.

F = qE

The force on a point charge in an electric field is the product of the charge and the field strength; direction depends on the sign of the charge.

Superposition (electric fields)

The net electric field from multiple charges is the vector sum of the individual fields.

Parallel-plate capacitor

Two large plates with equal and opposite charges that create a relatively uniform electric field between them.

Field strength between plates (in a capacitor)

The electric field between large, parallel plates is approximately constant and, for infinite plates, independent of the plate separation (E ≈ σ/ε0).

Field due to point charges

The electric field from a point charge falls off as 1/r^2 and points radially away from a positive charge and toward a negative charge.

Acceleration in an electric field

For a charge q in a field E, a = F/m = qE/m; acceleration depends on charge-to-mass ratio.

Proton in an electric field

A positive elementary charge that experiences a force in the direction of the field; acceleration depends on q/m.

Dipole in uniform field (motion)

A dipole experiences torque that tends to rotate it to align with the field; net force can be zero if the field is uniform.

Electric field vectors between charges

A visualization of field direction and relative strength; the resultant field is the vector sum of contributions from all charges.

Field strength near charges

Field magnitude is greatest near charges and where field lines are densest.

Charge distribution after touching identical spheres

When two identical conductors touch, charge distributes equally; upon separation, each sphere has half of the total charge.

Induction experiment with spheres (net charge by induction)

A demonstration where bringing a charged rod near neutral spheres redistributes charges; breaking contact while polarized can leave a net charge on the spheres.

Direction of electric field due to a positive charge

Electric field points away from a positive charge and toward a negative charge.

Electric field strength vs distance (point charges)

For a point charge, the field strength decreases with distance as 1/r^2; closer regions have stronger fields.

Electric field between two charges (superposition)

The resulting field is the vector sum of the fields from each charge, which can create regions of reinforcement or cancellation.

Zero net force in a dipole in a field

A perfectly oriented dipole in a uniform field experiences torque but no net translational force.

Field lines density and strength

The closer the field lines, the stronger the electric field in that region.

Charge redistribution on touching conductors

When conductors touch, free charges share equally if the conductors are identical; separation leaves equal charges on each.