<section>
<h2 class="title">Summary</h2>
<ul>
<li>
<p>The Doppler effect is a change in observed frequency due to the relative motion of a source and an observer.</p>
</li>
<li>
<p>The following equation can be used to calculate the frequency of the wave according to the observer or listener:</p>

\[{f}_{L}=\left(\frac{v+{v}_{L}}{v+{v}_{S}}\right){f}_{S}\]</li>
<li>
<p>If the direction of the wave from the listener to the source is chosen as positive, the velocities have the following signs:</p>
<table>
<tbody>
<tr>
<td>
<p>Source moves towards listener</p>
</td>
<td>
<p>${v}_{S}$: negative</p>
</td>
</tr>
<tr>
<td>
<p>Source moves away from listener</p>
</td>
<td>
<p>${v}_{S}$: positive</p>
</td>
</tr>
<tr>
<td> </td>
<td> </td>
</tr>
<tr>
<td>
<p>Listener moves towards source</p>
</td>
<td>
<p>${v}_{L}$: positive</p>
</td>
</tr>
<tr>
<td>
<p>Listener moves away from source</p>
</td>
<td>
<p>${v}_{L}$: negative</p>
</td>
</tr>
</tbody>
</table>
</li>
<li>
<p>The Doppler effect can be observed in all types of waves, including ultrasound, light and radiowaves (explored in another tutorial).</p>
</li>
<li>
<p>Sonography makes use of ultrasound and the Doppler effect to determine the direction of blood flow.</p>
</li>
</ul>
<h3>Table: Units used in <strong>Doppler effect</strong></h3>
<div>
<table summary="            ">
<tbody>
<tr>
<td colspan="3"><strong>Physical Quantities</strong></td>
</tr>
<tr>
<td><strong>Quantity</strong></td>
<td><strong>Unit name</strong></td>
<td><strong>Unit symbol</strong></td>
</tr>
<tr>
<td>Frequency ($f$)</td>
<td>hertz</td>
<td>$\text{Hz}$</td>
</tr>
<tr>
<td>Speed ($v$)</td>
<td>metres per second</td>
<td>$\text{m·s$^{-1}$}$</td>
</tr>
</tbody>
</table>
</div>
</section>

1c4ddb66-ad36-4f81-90e7-4629f497d0b4

Summary and Main Ideas

Physics is a science discipline concerned with the nature and properties of matter and energy. Physics topics include mechanics, heat, light and radiation, sound, electricity, magnetism, the structure of atoms, and so on.

Physics

Learn about the characteristics, properties, and behaviors of mechanical waves and sound, including transverse and longitudinal pulses, waves, and their superposition, as well as the speed, wavelength, amplitude, and frequency of sound waves, Doppler effect, and more in this tutorial.


Mechanical Waves and Sound

Characteristics Of A Sound Wave

Intensity of Sound

Introduction to Doppler Effect

Introduction to Sound Waves

Introduction to Transverse Pulses

Longitudinal Waves

Period And Frequency

Pulses: Amplitude And Length

Speed Of A Longitudinal Wave

Speed Of A Transverse Wave

Speed Of Sound

Summary of Doppler Effect

Summary of Longitudinal Waves

Summary of Sound

Summary of Transverse Pulses

Summary of Transverse Waves

Superposition Of Pulses

The Doppler Effect With Sound

The Physics Of Hearing

Transverse Waves

Ultrasound

Summary and Main Ideas

Track Your Learning Progress

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