<div>
<section>
<h2 class="title">Summary</h2>
<ul>
<li>
<p>Electromagnetic radiation has both a wave and a particle nature.</p>
</li>
<li>
<p>Electromagnetic waves travel at a speed of approximately $\text{3} \times \text{10}^{\text{8}}$ $\text{m·s$^{-1}$}$ in a vacuum.</p>
</li>
<li>
<p>The Electromagnetic spectrum consists of the following types of radiation: radio waves, microwaves, infrared, visible, ultraviolet, X-rays, gamma-rays.</p>
</li>
<li>
<p>Gamma-rays have the most energy and are the most penetrating, while radio waves have the lowest energy and are the least penetrating.</p>
</li>
</ul>
<div>
<table summary="            ">
<tbody>
<tr>
<td colspan="3">
<h3><strong>Physical Quantities</strong></h3>
</td>
</tr>
<tr>
<td>
<p><strong>Quantity</strong></p>
</td>
<td>
<p><strong>Unit name</strong></p>
</td>
<td>
<p><strong>Unit symbol</strong></p>
</td>
</tr>
<tr>
<td>
<p>Energy (E)</p>
</td>
<td>
<p>joule</p>
</td>
<td>
<p>J</p>
</td>
</tr>
<tr>
<td>
<p>Wavelength (λ)</p>
</td>
<td>
<p>metre</p>
</td>
<td>
<p>m</p>
</td>
</tr>
<tr>
<td>
<p>Period (T)</p>
</td>
<td>
<p>second</p>
</td>
<td>
<p>s</p>
</td>
</tr>
<tr>
<td>
<p>Frequency (f)</p>
</td>
<td>
<p>hertz</p>
</td>
<td>
<p>Hz ($\text{s$^{-1}$}$)</p>
</td>
</tr>
<tr>
<td>
<p>Speed of light (c)</p>
</td>
<td>
<p>metre per second</p>
</td>
<td>
<p>$\text{m·s$^{-1}$}$</p>
</td>
</tr>
</tbody>
</table>
<div>
<p><em>Table: Units used in <strong>electromagnetic radiation</strong></em></p>
</div>
</div>
</section>
</div>

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

Explore the properties and behaviors of electromagnetic waves, including their wave-like and particle-like nature, EM fields, penetrating abilities, diffraction, and the Doppler effect, and gain an understanding of the electromagnetic spectrum, animal behavior, 2D and 3D wavefronts, Huygen&#8217;s principle, and the expanding universe.


Physical Quantities
Quantity	Unit name	Unit symbol
Energy (E)	joule	J
Wavelength (λ)	metre	m
Period (T)	second	s
Frequency (f)	hertz	Hz (\(\text{s$^{-1}$}\))
Speed of light (c)	metre per second	\(\text{m·s$^{-1}$}\)

Summary and Main Ideas

Summary

Physical Quantities

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