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A negative frequency causes the sin function (violet) to lead the cos (red) by 1/4 cycle. The ambiguity is resolved when the cosine and sine operators can be observed simultaneously, because cos (ωt + θ) leads sin (ωt + θ) by cycle (i.e. radians) when ω > 0, and lags by cycle when ω < 0. Similarly, a vector, (cos ωt, sin ωt), rotates ...
Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio signals ( sound ), radio waves, and light . For example, if a heart beats at a frequency of 120 times per minute (2 hertz), the period—the interval between beats—is half a ...
Cyclotron resonance. Cyclotron resonance describes the interaction of external forces with charged particles experiencing a magnetic field, thus moving on a circular path. It is named after the cyclotron, a cyclic particle accelerator that utilizes an oscillating electric field tuned to this resonance to add kinetic energy to charged particles.
Photoelectric effect. Photoemission of electrons from a metal plate accompanied by the absorption of light quanta – photons. The photoelectric effect is the emission of electrons from a material caused by electromagnetic radiation such as ultraviolet light. Electrons emitted in this manner are called photoelectrons.
v. t. e. In electromagnetism, electromagnetic waves in vacuum travel at the speed of light c, according to Maxwell's Equations. The retarded time is the time when the field began to propagate from the point where it was emitted to an observer. The term "retarded" is used in this context (and the literature) in the sense of propagation delays .
Natural frequency, measured in terms of eigenfrequency, is the rate at which an oscillatory system tends to oscillate in the absence of disturbance. A foundational example pertains to simple harmonic oscillators , such as an idealized spring with no energy loss wherein the system exhibits constant-amplitude oscillations with a constant frequency.
The Nyquist–Shannon sampling theorem is a theorem in the field of signal processing which serves as a fundamental bridge between continuous-time signals and discrete-time signals. It establishes a sufficient condition for a sample rate that permits a discrete sequence of samples to capture all the information from a continuous-time signal of ...
The Rabi frequency is the frequency at which the probability amplitudes of two atomic energy levels fluctuate in an oscillating electromagnetic field. It is proportional to the transition dipole moment of the two levels and to the amplitude ( not intensity) of the electromagnetic field. Population transfer between the levels of such a 2-level ...