All Exams Test series for 1 year @ ₹349 only
Question

What is the relation between the frequency f, wavelength λ, and speed v of the sound?

The correct answer is

f = v/λ

Understanding the Relationship: Sound Frequency, Wavelength, and Speed

The question asks about the fundamental relationship connecting the frequency, wavelength, and speed of a sound wave. This relationship is a core concept in wave physics and applies to all types of waves, including sound waves.

Let's define the terms involved:

  • Speed (v): This is how fast the wave travels through the medium. For sound, this is the speed of sound. It is typically measured in meters per second (m/s).
  • Frequency (f): This is the number of wave cycles that pass a point in one second. It tells us how often a part of the wave oscillates. It is measured in Hertz (Hz), which is equivalent to cycles per second ($s^{-1}$).
  • Wavelength ($\lambda$): This is the distance between two consecutive identical points on a wave, such as peak to peak or trough to trough. It is the spatial length of one complete cycle. It is measured in meters (m).

The relationship between these three quantities for any wave is given by the wave equation:

\begin{equation*} v = f\lambda \end{equation*}

This equation states that the speed of the wave is equal to the product of its frequency and its wavelength.

The question asks for the relation when solving for the frequency (f). We can rearrange the wave equation ($v = f\lambda$) to isolate f:

Divide both sides of the equation by $\lambda$:

\begin{equation*} \frac{v}{\lambda} = \frac{f\lambda}{\lambda} \end{equation*}

This simplifies to:

\begin{equation*} f = \frac{v}{\lambda} \end{equation*}

This shows that the frequency of a wave is equal to its speed divided by its wavelength.

Let's look at the given options:

  1. f = v/λ
  2. f = λ v
  3. f = λ/v
  4. f = λv 2

Comparing our derived relationship ($f = v/\lambda$) with the options, we see that option 1 matches the correct relation.

Here is a summary of the variables and their standard units:

Quantity Symbol Standard Unit
Speed v meters per second (m/s)
Frequency f Hertz (Hz) or $s^{-1}$
Wavelength $\lambda$ meters (m)

Revision Table: Sound Wave Relationship

Understanding the formula $v = f\lambda$ is crucial for solving problems involving sound waves and other types of waves. Remember that while frequency and wavelength can change when a wave moves from one medium to another, the frequency usually remains constant (determined by the source), and the speed and wavelength adjust accordingly.

Additional Information: Properties of Sound Waves

Sound waves are longitudinal waves, meaning the particles of the medium vibrate parallel to the direction of energy transfer. The speed of sound depends on the properties of the medium it travels through, such as its density and compressibility. For example, sound travels faster in solids than in liquids, and faster in liquids than in gases. Temperature also affects the speed of sound in a gas; the speed increases with increasing temperature.

Was this answer helpful?

Important Questions from The Speed of Sound

  1. The speed of a longitudinal wave in a solid bar is given by v = √(X/ρ), where 'ρ' is density of the medium. What is the unknown term 'X'?

  2. At standard temperature and pressure, in which of the following media does sound propagate with the greatest speed?

  3. The velocity of sound in air is affected by change in the

    I. Moisture content of air

    II. Temperature of air

    III. Composition of air

    IV. Atmospheric pressure

    Choose the correct answer.

  4. Velocity of sound is maximum in:

  5. An object is 10.64 km below the sea level. A research team sends down a sonar signal to confirm this depth. After how long can it expect to get the echo? Take speed of sound in sea water = 1520 m/s.

Need Expert Advice?

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App