Frequency (f, v) is repeating event's number of occurrences per unit of time, measured in Hertz (Hz). It's crucially used in science and engineering to specify rate of oscillatory and vibratory phenomena, like mechanical vibrations, audio signals (sound), radio waves, and light.
The interval of time between events is called a period. It's the frequency's reciprocal.
[1] A pendulum making 25 complete oscillations in 60 s, a frequency of 0.416 Hz
Frequency formula: 1/s = f
E.g. A 10 Hz lamp blinks 10 times a second (s).
Therefore, period (T) formula is: 1/f = s
E.g. That lamp blinks each 1/10 = 0.1 s = 100 ms
[2.1]
Frequency is the idea of a waveform.
Frequency categories are for instance electromagnetic frequencies (like radio waves, microwaves, light, etc.), audio frequencies (describing sound), and frequency distributions (used in statistics).
Cutoff frequency:
Natural frequency: The rate at which a system vibrates on its own.
Resonant frequency: Frequency at which a system resonates.
Fundamental frequency: Lowest frequency of a periodic wave.
Harmonic frequencies: Multiples of the fundamental frequency.
Cutoff Frequency: Frequency where a system’s response drops significantly (filters).
Carrier Frequency: Frequency of a carrier wave in communication.
Modulation Frequency: Frequency used to modulate a carrier wave.
Sampling Frequency: Rate at which a signal is sampled in digital systems.
Doppler Frequency: Frequency change due to relative motion.
Beat Frequency: Resultant frequency from interference of two close frequencies.
A cutoff frequency is the frequency a system (like a filter/circuit) starts to significantly reduce the signal, categorized based on the filter type as
Low-pass filter (LPF) allows frequencies below the cutoff; attenuates higher frequencies.
High-pass filter (HPF) allows frequencies above the cutoff; attenuates lower frequencies.
Band-pass filter (BPF) allows frequencies within a range (between lower and upper cutoff); attenuates outside that range.
Band-stop/Notch filter (BSF/Notch) blocks frequencies within a range; allows others.
It's often defined at the point a signal drops to 70.7% of its max amplitude (-3 decibells).
[2.1] Human ears are sensitive between frequency of 20-20,000 Hz. One with hearing loss means that they can't hear some frequency.
All souds are frequency
[2.1] The left TV has a 60 Hz frequency--it refreshes the screen 60 times a second. The right TV is at 240 Hz, it updates the screen 240 times a second.
[2.1] Music comprises of various frequency and signal shapes. A violon tuned to the A string vibrates at 440 Hz. Which is how we can make music via lightning bolts from a Tesla coil.
To hear in A string, the coil just shoots 440 lightning bolts per second.
A speaker starting at 1 Hz only makes a 1 s sound slowly. Increasing its frequency brings sound closer, gradually sounding like musics.
Higher frequency makes higher notes, so certain frequency correspond to a note.
E.g. Middle C note is 261.6 Hz.
[1] Wikipedia
[2.1] Audio frequency
[2.3] Chirp
[2.4] Cutoff frequency
[2.5] Downsampling
[2.6] Electronic filter
[2.7] Fourier analysis
[2.8] Frequency band
[2.9] Frequency converter
[2.10] Frequency domain
[2.11] Frequency distribution
[2.12] Frequency extender
[2.13] Frequency grid
[2.14] Frequency level
[2.15] Frequency modulation
[2.16] Frequency spectrum
[2.17] Interaction frequency
[2.19] Natural frequency
[2.20] Negative frequency
[2.21] Periodicity (disambiguation)
[2.22] Pink noise
[2.23] Preselector
[2.24] Radar signal characteristics
[2.25] Radio frequency
[2.27] Spread spectrum
[2.28] Spectral component
[2.29] Transverter
[2.30] Upsampling
[2] Wave Period and Frequency - YT
[2.1] What is Frequency?
[2.2]
[2.3]