Physics Fields Review

Flashcards covering key physics concepts, including fields, electric fields, magnetic fields, electromagnetism, and gravitational fields.

Fields

Fields (gravitational, electric, magnetic) help explain forces acting at a distance without direct contact.

Inverse-square law

Field strength decreases with the square of the distance: F ∝ 1/r^2.

Field theory

Describes how forces act over space without physical contact between objects.

Field strength

Tells us how much force a field would exert on a unit object.

Electric fields

Electric fields (E) cause forces on charges (q), with F = qE.

Electric fields follow inverse-square law

E = kQ/d^2, where Q is the source charge and d is the distance.

Electric field lines (positive charges)

Point away from positive charges.

Electric field lines (negative charges)

Point toward negative charges.

Electric field lines (density)

Denser lines indicate a stronger field.

Coulomb’s Law

F = (k * q1 * q2) / d^2

Electromagnetic force

One of the four fundamental forces; includes both electric and magnetic forces acting on charged particles.

Electric & magnetic fields relationship

Changing electric fields create magnetic fields (and vice versa).

Right-hand rule

Thumb = current, fingers = magnetic field.

Northern Lights

Charged particles from the sun hit Earth’s magnetic field, get funneled to the poles, and excite atmospheric gases.

Electromagnetism principle (current)

Current produces magnetic field.

Electromagnetism principle (magnetic fields)

Magnetic fields can produce current (Faraday’s Law).

Tech & environmental impact (positive)

Power generation, MRI machines, data storage.

Tech & environmental impact (negative)

Migration interference, potential health risks.

Gravitational lensing

Massive objects bend light (lensing).

Dark matter

Inferred by gravity effects.

Universe expansion

Universe is expanding – gravitational fields play a role in understanding time and space.

Gravitational field near Earth

g ≈ 9.8 m/s^2, varies slightly by altitude and latitude.

Mass

Mass = amount of matter (kg).

Weight

Weight = force of gravity (N): W = mg.

Variation in gravitational field strength

Farther from center of mass → weaker gravity.

Weightlessness

Astronauts are not truly “weightless”—they’re in free fall, orbiting Earth.

Microgravity & science

Allows unique experiments in biology, physics (e.g., protein crystallization, fluid dynamics).

Gravitational field strength formula (g)

g = Gm/r^2

Gravitational field strength formula (F)

F = (Gm1m2)/r^2