Ripple Tank Summary Why Ripple Tanks Real waves

Ripple Tank Summary

Why Ripple Tanks : • Real waves (sound, light, radiation) are difficult to observe • Properties of waves should be independent of the type of wave • Water waves (which are easy to see) provide a useful analogy for other types of waves

Wave Properties • Transmission • Reflection • Refraction • Diffraction • Interference

Transmission • The traveling of a wave through a medium away from a vibrating source

Transmission • The wavelength of the generated wave does not change as it travels the length of the ripple tank • The speed of the wave remains a constant

Transmission • If the medium doesn’t change the speed must remain constant • A change in the frequency must result in a change in the wavelength • An increase in the frequency causes a shortening of the wavelength

Reflection • The changing direction of a wave upon impact with a barrier or object

Reflection • The speed of the wave, frequency and wavelength remains unchanged after reflection • Only the direction of the wave changes

Reflection • The direction of the wave changes such that the angle of incidence is equal to the angle of reflection

Refraction • Refraction is the bending of a wave as it passes from one type of medium into another type of medium

Refraction • As the surface waves travel from a deep to shallow environment the waves will bend and decrease in wavelength.

Refraction • Since the frequency of the waves can not change and the wavelength decreases, the speed of the wave as it travels from a deep section to a shallow section must decrease as well. This causes the waves to “pile up” on one another. • Tsunami

Refraction • This bending of the wave and the resultant change in speed has environmental implications!

Diffraction • The bending of a wave as it either passes by a barrier / object OR the spreading out of a wave as it passes through an opening

Diffraction • Longer wavelengths diffract easier around a barrier compared to shorter wavelengths • This is seen in the difference between light (a short wavelength) and sound (a long wavelength)

Diffraction • Waves can also diffract (bend) as they pass through an opening • Maximum diffraction occurs when the width of the slit is close to the wavelength of the energy

Diffraction • Diffraction is often used in creating wave breaks to help dissipate the incoming energy of the wave

Interference • The total disturbance within a medium when more than one wave is present

Interference • The amplitudes of the waves will add together as vectors. • A crest plus a crest forms a much larger crest • A trough plus a trough form a deeper trough

Interference • If a crest and crest (trough and trough) add together we end up with constructive interference

Interference • If a crest adds to a trough (or trough to a crest) we end up with destructive interference

Interference • In most cases we end up with partial interference creating a beat.

Interference • Many objects display an interference pattern (such as electrons)