Difference Between Amplitude and Frequency

Amplitude and frequency are fundamental concepts in the study of periodic motion. While both describe characteristics of oscillatory phenomena, they represent distinct aspects of the motion. Amplitude refers to the maximum displacement of a wave or oscillating object from its equilibrium position that reflects its intensity or strength. On the other hand, frequency denotes the rate at which the motion repeats itself, indicating how often an event occurs within a specified period of time.

In this article, we will learn the differences between amplitude and frequency in detail.

What is Frequency?

Frequency is a concept used in physics and engineering to describe how often a repetitive wave oscillates or vibrates within a specific time frame. It is measured in hertz (Hz), which represents the number of cycles per second. For example, if a pendulum swings back and forth 10 times in one minute, its frequency is 0.17 Hz. This means it completes 0.17 cycles, or oscillations, every second.

What is Amplitude?

Amplitude is a concept in physics that shows the maximum deviation of a wave from its equilibrium position. It is measured in meters or feet, depending on the wave type. In simple terms, we can say amplitude represents the peak height of a wave from its baseline. For example, if a water wave has an amplitude of 3 feet, it implies that it fluctuates between a minimum of 1 foot below and a maximum of 2 feet above its baseline.

Difference Between Amplitude and Frequency

The difference between amplitude and frequency can be understood from the table given below:

Basis	Amplitude	Frequency
Definition	Maximum displacement from equilibrium point in a periodic motion.	Number of complete cycles occurring per unit time in a periodic motion.
Relationship	Amplitude depends on the total mechanical energy of the system.	Frequency depends on how often an event occurs.
Symbol	It is represented by the letter “A”.	It is represented by the letter “f”.
Measurement Unit	It is measured in meters or another unit of displacement.	It is measured in Hertz (Hz), indicating cycles per second.
Significance	It describes the intensity or strength of the oscillation in a periodic motion.	It describes how often the periodic motion repeats itself.
Relation to Energy	At maximum displacement (amplitude), kinetic energy is zero and potential energy is maximum.	Frequency does not directly relate to energy but to the rate of occurrence of events in a periodic motion.
Effect on Wave	Affects the wave’s height or intensity.	Affects the wave’s frequency or pitch.
Formula	x = A sin(ωt + φ) where A is amplitude	f= 1/T, where T represents the period of the motion, which is the time taken for one complete cycle.
Example	For a spring-mass system, amplitude is determined by the total mechanical energy and spring constant.	The frequency of a planet orbiting around the sun indicates how often it completes one orbit.

Effect of Frequency and Amplitude on Sound

A sound wave with a shorter wavelength has a higher frequency, which means it has a higher pitch and cycles more quickly. Conversely, a longer wavelength has a lower frequency, resulting in a lower pitch and slower cycles.

For instance, when you pluck a guitar string near its end, it produces a sound with a higher pitch because the string’s vibrations are faster. But when you pluck it near its center, it produces a sound with a lower pitch because the vibrations are slower.

FAQs on Difference Between Amplitude and Frequency

Does Amplitude affect Frequency?

No, amplitude does not directly affect frequency. Amplitude refers to the maximum displacement of a wave from its equilibrium position, while frequency refers to the number of complete cycles of the wave occurring per unit time. These are independent properties of a wave, and changes in amplitude do not alter the frequency of the wave.

What if a wave has a higher amplitude?

If a wave has a higher amplitude, it means that the maximum displacement of the wave from its equilibrium position is greater. This can result in a louder sound or a more intense wave, but it does not change the frequency of the wave.

What is the difference between amplitude and wavelength?

The difference between amplitude and wavelength is:

• Amplitude refers to the maximum displacement or distance from the equilibrium position in a wave. It represents the intensity or strength of the wave.
• Wavelength, on the other hand, is the distance between two consecutive points in a wave that are in phase, such as from crest to crest or trough to trough. It represents the spatial period of the wave.

What is SI unit of frequency?

The SI unit of frequency is the hertz (Hz). One hertz equals one cycle per second, indicating the number of oscillations or cycles of a wave occurring in one second.

What is the SI unit of amplitude?

The SI unit of amplitude depends on the type of wave being considered. For mechanical waves, such as sound waves, the amplitude is typically measured in meters (m). For electromagnetic waves, such as light waves, the amplitude is measured in volts per meter (V/m).

What is the symbol for frequency?

The symbol for frequency is 𝑓. It is commonly used to represent the number of cycles or oscillations of a wave per unit time.

What is the symbol for amplitude?

The symbol for amplitude varies depending on the context of the wave being described. In general, it is represented by A.

What is the formula for frequency and amplitude?

The formula for frequency (f) is: f= 1/T​ where T is the period of the wave, representing the time taken for one complete cycle.

The formula for amplitude (A) depends on the type of wave. For simple harmonic motion, such as in a sine wave, the amplitude is the maximum displacement from equilibrium and can be calculated using specific equations for different systems. For example, in a mass-spring system, the amplitude (A) is equal to the maximum displacement of the mass from its equilibrium position.