Waves: Exploring Structures Using Waves

Features of All Waves

All waves transfer energy and information without transferring matter.
Waves are categorised as either transverse or longitudinal, based on their direction of vibration compared to the direction of energy transfer.
Transverse waves include light and all electromagnetic waves, ripples on water, and waves on a string. They vibrate perpendicular to the direction of energy transfer.
Longitudinal waves include sound waves and ultrasound waves. They vibrate parallel to the direction of energy transfer.
A wave cycle involves a complete vibration consisting of one peak and one trough in transverse waves, or one compression and one rarefaction in longitudinal waves.

Waves can undergo several behaviours including reflection, refraction, diffraction and interference.
Reflection involves the bouncing back of waves when they hit a reflective surface, leading to an echo or the formation of an image in a mirror.
Refraction is the change of direction and speed of a wave when it enters a different medium, leading to bending of waves.
Diffraction is the spreading out of waves when they pass through a gap or around obstacles. This behaviour is more prominent when the gap is comparable to the wavelength of the waves.
Interference refers to the interaction of two waves meeting, resulting in constructive (increasing amplitude) or destructive (decreasing amplitude) interference.

The wavelength is the distance from a point on one wave to the identical point on the next wave, for example, from one peak to the next peak.
The frequency of a wave is the number of waves produced or passing a point in one second, and it’s measured in Hertz (Hz).
The amplitude is the maximum displacement of a point on the wave from its undisturbed position, in other words, the height from the middle line to the peak in a transverse wave or compression in a longitudinal wave.
The speed of the waves can be calculated using the equation: wave speed = frequency x wavelength.

Several fields like medicine, engineering and communications use waves to observe structures and phenomena that are otherwise impossible.
Ultrasound waves are used for medical imaging and treatment as they can pass through body tissues and reflect back at boundaries to create images.
Seismic waves encountered in the study of earthquakes provide vital information about the structure of the Earth’s interior.
Electromagnetic waves, including light, enable us to create images of galaxies billions of light years away, as well as of minuscule structures within cells.

The behaviour and properties of waves can be explored with practical experiments like the ripple tank for water waves.
Investigations of reflection and refraction can be done with light-box experiments.
Sound wave experiments can involve exploration of pitch and volume with musical instruments.
Through these experiments, one can prove the relationships and behaviours of waves, and validate the wave equation, v = f λ.