Frequency
The number of complete oscillations (or wave cycles) per unit time, measured in hertz (Hz), where 1 Hz = 1 cycle per second. Denoted by f, frequency is related to period by f = 1/T. For progressive waves, frequency relates to wavelength and speed by f = v/λ.
Formula
f = 1/T
Real World
A standard piano middle C string vibrates at 261.6 Hz, completing 261.6 full oscillations every second — doubling this frequency produces the C one octave higher.
Exam Focus
State that frequency is unchanged when a wave crosses a boundary; examiners commonly probe this misconception.
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