Terms starting with F
35 terms · page 2 of 2
Fourier Transform
Mathematical & Computational Physics
Inverse Domain Unit (e.g. s⁻¹ or m⁻¹)
An integral transform that decomposes a continuous time or spatial signal into its constituent frequency or wavevector spectrum.
f̂(k) = ∫_(-∞)^(∞) f(x) e^(-i k x) dx, f(x) = (1 / 2π) ∫_(-∞)^(∞) f̂(k) e^(i k x) dk
Frame of Reference
Foundations of Physics
N/A
A coordinate system along with a clock used to record positions, velocities, and times of physical events.
Franck-Hertz Experiment
Quantum & Atomic Physics
eV (Electron-Volts)
An influential 1914 physics experiment that directly demonstrated the existence of quantized discrete energy states in mercury atoms.
E_loss = h ν = 4.9 eV (for Mercury vapor)
Fraunhofer Diffraction
Optics
m
Far-field wave diffraction where both incident and observed wavefronts are planar, achieved using lenses or large distances.
a sin θ = m λ
Fraunhofer Lines
Optics
nm
A set of dark absorption lines in the solar spectrum caused by chemical element absorption in the Sun's outer atmosphere.
E = h ν = E_upper - E_lower
Frequency
Waves, Oscillations & Acoustics
Hz (s⁻¹)
The number of complete wave cycles or vibrational repetitions occurring per unit time.
f = 1 / T = v / λ
Frequency (Mechanics)
Classical Mechanics
Hz (s⁻¹)
The number of complete vibrational cycles occurring per unit time.
f = 1 / T = ω / (2π)
Fresnel Diffraction
Optics
N/A
Near-field wave diffraction where source or observation screen is close to the diffracting aperture, requiring spherical wavefront curvature analysis.
Fresnel Number F = a² / (λ L) ≳ 1
Friction
Classical Mechanics
N
A resistive contact force that opposes relative sliding motion or tendency of motion between surfaces.
fs ≤ μs N, fk = μk N
Fundamental Constants
Foundations of Physics
Various
Universal physical quantities whose numerical values are constant in space and time throughout the cosmos.
Fundamental Frequency
Waves, Oscillations & Acoustics
Hz
The lowest natural frequency at which a standing wave pattern can be established in a vibrating system.
f1 = v / (2 L) (String / Open Pipe)