Comparing Light to Sound: Reflections and More
Educational and Fun Activities
Written by Alexandra Stone
29 October 2024
🕓 10 min
The natural phenomena of light and sound are fascinating to children and adults alike, yet these two essential aspects of our world behave in distinct ways. Understanding how light and sound work – from reflections to waves – can offer children a foundational grasp of physics and the natural environment. At the Science of Sound, we explore sound science with young learners through hands-on activities and multi-sensory experiences, allowing them to appreciate the similarities and differences between light and sound while engaging in fun scientific experiments.
The Basics: Light and Sound as Waves
Both light and sound travel in waves, but the nature of these waves differs significantly. Sound waves are mechanical waves, meaning they require a medium (like air, water, or solids) to travel through. When we speak, for example, sound waves created by our vocal cords move through the air, and when these waves reach another person’s ear, they are interpreted as sound. Without a medium, such as in a vacuum, sound cannot travel, which is why space is silent. Light, on the other hand, travels in electromagnetic waves that do not need a medium, allowing it to travel through the vacuum of space. Light waves are much faster than sound waves, moving at an astounding speed of 299,792 kilometres per second compared to sound’s 343 metres per second in air. This vast difference in speed is why we see lightning before we hear thunder, even though both happen simultaneously.
These differences between light and sound waves form the basis of various engaging educational activities at the Science of Sound. Children can experiment with different mediums to see how sound changes as it moves through air, water, or solids. This hands-on exploration helps young learners understand the nature of sound and contrast it with light’s unique ability to travel across empty space. Through activities like these, children not only gain a clearer understanding of wave properties but also develop an appreciation for the wonders of physics in everyday life.
Reflecting on Reflections: How Light and Sound Bounce Back
One of the most exciting aspects of comparing light and sound is observing their reflections. Light reflections are something we experience every day, whether it’s seeing our image in a mirror or light bouncing off a shiny surface. When light hits a smooth, reflective surface, it bounces back in a predictable manner according to the angle of incidence and reflection. This phenomenon is called specular reflection, where light rays bounce off a surface at the same angle they hit it. This is why we can see our reflection in a mirror but not on rough surfaces like paper or wood, which scatter light in multiple directions.
Sound also reflects, but it behaves differently due to its nature as a mechanical wave. When sound waves hit a surface, they bounce back, creating an echo if the surface is sufficiently distant from the sound source. Echoes are more noticeable in larger spaces or with hard surfaces, as these materials do not absorb much sound, allowing it to bounce back clearly. For example, in an empty hall or a cave, the sound of your voice will echo as it reflects off the walls. However, in a room with carpets, furniture, and curtains, sound reflections are absorbed, reducing the likelihood of an echo.
At the Science of Sound, we bring these concepts to life with experiments that allow children to observe reflections of both light and sound. Activities like creating a simple echo in an empty hallway or experimenting with flashlights and mirrors help young learners understand reflection principles. Through these activities, children discover how different materials and surfaces affect the behaviour of light and sound, laying a foundation for future scientific inquiry.
Absorption and Diffusion: How Light and Sound Interact with Surfaces
While reflection plays a significant role in how we perceive light and sound, absorption and diffusion are equally important in understanding their behaviour. Absorption occurs when a material takes in light or sound rather than reflecting it back. For light, absorption happens when light waves encounter a surface that absorbs some or all of the light’s energy. Darker materials absorb more light, which is why black objects tend to get hotter in the sun than lighter-coloured ones that reflect more light.
Sound, too, can be absorbed by various materials, especially those that are soft or porous, like carpets, curtains, and foam panels. These materials trap sound waves, preventing them from bouncing back and reducing echoes. In fact, soundproofing a room relies heavily on using materials that absorb sound effectively. Diffusion, on the other hand, occurs when light or sound spreads out after hitting a surface. With light, diffusion scatters rays in multiple directions, softening the appearance of reflections. Sound diffusion occurs similarly, making a space sound more balanced and reducing sharp echoes.
At Science of Sound sessions, children experiment with different materials to explore sound absorption and diffusion. For example, they might test how sound changes in a room with hard walls versus one with soft surfaces, noting the difference in echoes and clarity. With light, we conduct similar experiments by shining light on different colours and textures, allowing children to observe how light reflects, absorbs, or diffuses. Through such experiments, children understand how materials influence the perception of light and sound, developing a scientific curiosity about everyday materials and surfaces.
Frequency and Pitch vs. Colour and Brightness
Light and sound differ in how they express their wave frequencies. Frequency determines sound’s pitch – higher frequencies produce higher pitches, while lower frequencies result in lower pitches. For instance, a soprano singer’s voice has a high pitch, while a bass guitar produces lower frequencies and therefore lower pitches. In terms of light, frequency is associated with colour. The visible spectrum of light includes various colours, each representing a different frequency, from low-frequency reds to high-frequency blues and violets.
Brightness and loudness are also comparable. Loudness in sound is determined by a wave’s amplitude – the higher the amplitude, the louder the sound. Similarly, brightness in light is determined by the intensity of the light waves. Brighter light has a higher amplitude, making it appear more intense to our eyes. For children, this connection between sound and light properties is intriguing, as it links the concepts of colour, brightness, pitch, and volume.
The Science of Sound brings these scientific principles to life through interactive demonstrations. Children experiment with sound frequencies using musical instruments, observing how different notes produce different pitches, just as colours represent various frequencies in light. By exploring the relationships between frequency, pitch, and colour, young learners gain a deeper understanding of the complex nature of sound and light. This approach enhances their scientific literacy and lays the groundwork for future explorations in physics and sensory sciences.
Conclusion: Experience the Science of Sound First-hand
Understanding the similarities and differences between light and sound opens a world of curiosity for children. At the Science of Sound, we’re dedicated to providing engaging educational experiences that teach children about these fascinating principles through hands-on activities, demonstrations, and experiments. Our workshops, holiday camps, and after-school programmes offer children the opportunity to learn through real-world applications of sound and light science, sparking curiosity and excitement about physics.
If your child enjoyed learning about sound and light, they’ll love our upcoming Science of Sound holiday camp. Designed to deepen children’s understanding of science in a fun and interactive way, our camp is the perfect place to explore, create, and discover the wonders of light, sound, and more. Find out more and join us for an unforgettable scientific journey!
