<h2>What is a <em>pulse</em>?</h2>
<div class="ns-school-emp">
<h3>Optional Investigation: Observation of Pulses</h3>
<div class="ns-school-defn">
<p>Take a heavy rope. Have two people hold the rope stretched out horizontally. Flick the rope at one end only once.</p>
<img alt="39ddb190cd1fb636ecd25a71884037c1.png" src="https://data.ulearngo.com/assets/1fc5a357-708c-4d36-89ef-cc7d4f41a834"/>
<p>What happens to the disturbance that you created in the rope? Does it stay at the place where it was created or does it move down the length of the rope?</p>
</div>
</div>
<p>In the activity, we created a <em>pulse</em>. A pulse is a <em>single</em> disturbance that moves through a medium. In a transverse pulse the displacement of the medium is perpendicular to the direction of motion of the pulse. The figure below shows an example of a transverse pulse. In the activity, the rope or spring was held horizontally and the pulse moved the rope up and down. This was an example of a transverse pulse.</p>
<div class="ns-school-emp">
<h3>Definition: Pulse</h3>
<div class="ns-school-defn">
<p>A pulse is a single disturbance that moves through a medium.</p>
</div>
</div>
<div class="ns-school-emp">
<h3>Definition: Transverse Pulse</h3>
<div class="ns-school-defn">
<p>A pulse where all of the particles disturbed by the pulse move perpendicular (at a right angle) to the direction in which the pulse is moving.</p>
</div>
</div>
<section>
<h2 class="title">Pulse length and amplitude</h2>
<p>The amplitude of a pulse is a measurement of how far the medium is displaced momentarily from a position of rest. The pulse length is a measurement of how long the pulse is. Both these quantities are shown in the figure below.</p>
<div class="ns-school-emp">
<h3>Definition: Amplitude</h3>
<div class="ns-school-defn">
<p>The amplitude of a pulse is the maximum disturbance or distance the medium is displaced from its rest (equilibrium) position.</p>
<p>Quantity: Amplitude (A)         Unit name: metre         Unit symbol: m</p>
</div>
</div>
<div class="wp-caption alignnone" style="width: 477px"><img alt="4cb62070275114c3dcd95463c2a1f224.png" height="170" src="https://data.ulearngo.com/assets/80c337b4-057c-4477-ae39-823b6fa8ce0a" width="477"/><p class="wp-caption-text">Example of a transverse pulse</p></div>
<p>The position of rest is the position the medium would be in if it were undisturbed. This is also called the equilibrium position. People will often use rest and equilibrium interchangeably.</p>
<div class="ns-school-emp">
<h3>Optional Investigation: Pulse Length and Amplitude</h3>
<div class="ns-school-defn">
<p>The graphs below show the positions of a pulse at different times.</p>
<img alt="db228a4c65c67882724ab61c8cedf839.png" src="https://data.ulearngo.com/assets/a647c616-309a-44f0-bbbc-148f52ce7155"/>
<p>Use your ruler to measure the lengths of \(A\) and \(p\). Fill your answers in the table.</p>
<div>
<table>
<tbody>
<tr>
<td>Time</td>
<td>\(A\)</td>
<td>\(p\)</td>
</tr>
<tr>
<td>\(t = \text{0}\text{ s}\)</td>
<td> </td>
<td> </td>
</tr>
<tr>
<td>\(t = \text{1}\text{ s}\)</td>
<td> </td>
<td> </td>
</tr>
<tr>
<td>\(t = \text{2}\text{ s}\)</td>
<td> </td>
<td> </td>
</tr>
<tr>
<td>\(t = \text{3}\text{ s}\)</td>
<td> </td>
<td> </td>
</tr>
</tbody>
</table>
</div>
<p>What do you notice about the values of \(A\) and \(p\)?</p>
</div>
</div>
</section>
<p>In the activity, we found that the values for how high the pulse (\(A\)) is and how wide the pulse (\(p\)) is the same at different times. <em>Pulse length</em> and <em>amplitude</em> are two important quantities of a pulse.</p>

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Pulses: Amplitude and Length

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.

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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.


Pulses: Amplitude and Length

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