What Is Amplitude?

Amplitude refers to the maximum value that the physical quantity of vibration can reach, usually expressed as A. It is a physical quantity representing the range and intensity of vibration.

Amplitude refers to the maximum value that the physical quantity of vibration can reach, usually expressed as A. It is a physical quantity representing the range and intensity of vibration.

Chinese name

amplitude

Foreign name

amplitude

Alias

amplitude

Conceptual category

Physics; sports; other

Amplitude definition

Amplitude refers to the maximum value that the physical quantity of vibration can reach, usually expressed as A. It is a physical quantity representing the range and intensity of vibration.

In mechanical vibration, the amplitude is the absolute value of the maximum displacement from the equilibrium position when the object is vibrating, and the amplitude is numerically equal to the magnitude of the maximum displacement. Amplitude is a scalar and the unit is expressed in meters or centimeters. Amplitude describes the magnitude of the vibration amplitude of the object and the strength of the vibration.

In AC circuits, the current amplitude or voltage amplitude refers to the maximum value of the current or voltage change, also called the peak value of the voltage or current.

In acoustic vibration, the amplitude is the maximum of the difference between sound pressure and static pressure. The amplitude of a sound wave is measured in decibels. The magnitude of the sound wave amplitude can determine the sound intensity.

The amplitude of a simple resonance is constant, and it is a constant determined by the initial conditions (initial displacement and initial velocity) of the resonance. The energy of the resonance is proportional to the square of the amplitude. Therefore, the square of the amplitude can be used as a sign of the strength of the resonance. The amplitude of the stable phase of the forced vibration is also a constant, and the amplitude of the damped vibration is gradually reduced. ^[1]

Amplitude related concepts

Amplitude is a characteristic physical quantity of vibration. Some important concepts related to this are as follows:

cycle

The elapsed time for an object to complete a full vibration is a period T, and its unit is second. The period is a physical quantity that indicates how fast the particle vibrates. The longer the period, the slower the vibration.

frequency

The number of full vibrations completed by the vibrating particle within one second is called the frequency of the vibration, and its unit is hertz (Hz). Frequency is also a physical quantity that indicates how fast the particle vibrates. The larger the frequency, the faster the vibration. The relationship between period and frequency or its unit relationship is 1Hz = 1S ^ (-1) Natural frequency and natural period The vibration frequency (period) of simple harmonic motion is determined by the nature of the vibrating object itself, so it is also called natural frequency (natural period ). The frequency of the sound waves determines the pitch of the sound.

Full vibration

After a full vibration of the vibrating particle, its vibrating state returns to its original state.

Emphasis: "Restore to the original state" refers to a state with the same size and direction as the original position, speed, displacement, acceleration, etc. Therefore, the distance travelled by a vibrating object during a full vibration is 4A.

other

The vibration frequency (period) of a simple harmonic motion is independent of the amplitude of the vibration. For the same vibration system, the amplitude of the vibration can be changed, and the frequency (period) of the vibration is constant.

The natural frequency natural period is relative to the "driving power frequency, driving force period" in resonance.

Amplitude amplitude modulation

Also known as amplitude modulation, amplitude modulation, AM (Amplitude modulation), refers to the modulation method to make the amplitude of the carrier wave change according to the required transmission signal, but the frequency remains unchanged. AM is widely used in wired or radio communications and broadcasting. ^[2] Generally, a higher frequency signal is used at the modulation end, and its vibration amplitude changes with a certain function relationship with the modulation signal, and then the modulation is performed at the demodulation end.

The advantage of amplitude modulation is that the amplitude information of low-frequency signals can be included in the high-frequency carrier signal, which is conducive to signal propagation.