## Speed of a Travelling Wave – Class 11 | Chapter – 9 | Physics Short Notes Series PDF for NEET & JEE

Speed of a Travelling Wave: The speed of a travelling wave is determined by the properties of the medium through which the wave is traveling. The speed of a wave is the distance traveled by the wave per unit time and is often denoted by the letter v.

## Speed of a Travelling Wave

The speed of a wave can also be determined by the medium’s properties, such as its density, elasticity, and temperature. For example, in a string wave, the speed of the wave is determined by the tension in the string and its mass per unit length.

For a wave traveling through a medium with a constant density and elasticity, the speed of the wave can be determined by the equation:

v = fλ

where f is the frequency of the wave and λ is its wavelength. This equation is known as the wave equation.

## Properties of Speed of a Travelling Wave

The speed of a travelling wave has several important properties, including:

• Dependence on the medium: The speed of a wave is determined by the properties of the medium through which it is traveling. For example, the speed of sound waves in air is different than the speed of sound waves in water.
• Dependence on wavelength and frequency: The speed of a wave is directly proportional to its wavelength and frequency, as given by the equation v = fλ. This means that waves with shorter wavelengths and higher frequencies travel faster than waves with longer wavelengths and lower frequencies.
• Invariance with respect to amplitude and shape: The speed of a wave is not affected by the wave’s amplitude or shape, as long as the medium through which it is traveling remains constant. This means that two waves with the same frequency and wavelength, but different amplitudes, will travel at the same speed.
• Limitations in some media: The speed of a wave may be limited in some media. For example, electromagnetic waves (such as light) have a maximum speed of 299,792,458 meters per second in a vacuum, which is known as the speed of light.
• Direction of propagation: The speed of a wave is always in the direction of propagation. This means that a wave that is traveling in one direction cannot suddenly change direction and travel in another direction at the same speed.

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