Waves

Transverse Waves 

In transverse waves, the oscillations are perpendicular (at right angles) to the direction of energy transfer. Not all transverse waves require a medium.

Longitudinal Waves

In longitudinal waves, the oscillations are parallel to the direction of energy transfer. All longitudinal waves require a medium to travel in.

Amplitude

The amplitude of a wave is the maximum displacement of a point on a wave away from its undisturbed position.

Wavelength

The wavelength of a wave is the distance from a point on one wave to the equivalent point on the adjacent wave.

Frequency

The frequency is the number of waves passing a point each second, and the unit of frequency is the Hertz (Hz). 1 Hz = one wave per second.

Period

The period is the time in seconds for one wave to pass a point. We can calculate the period using this equation: period (s) = 1 / frequency (Hz) (T = 1 / f)

Wave Speed

The wave speed is the speed at which the wave moves through the medium, in other words, the speed at which energy is transferred. We can calculate wave speed using this equation: wave speed (m/s) = frequency (Hz) x wavelength (m) (v = f x λ). We can then calculate the speed of the sound waves by dividing the distance travelled by the time taken.

Ripple Tank Practical

A ripple tank is used to observe the features of water waves. A ripple tank is a shallow tray of water and in the water is a vibrating bar. The bar is connected to a power pack. When the bar vibrates it creates waves across the surface of the water above the ripple tongue. To measure the wavelength, we place a ruler on the paper. We then freeze the image of the waves then measure the distance between one wave and 10 waves further in other words a total of 10 wavelengths.

In this case, 10 wavelengths equal 26 centimeters, in other words, 0.26 meters. To find one wavelength, we now divide this by 10. This gives us a value of 0.026 meters for the wavelength of these waves.

Another way to determine the wave speed is to select a wave and then measure the time it takes to move the length of the tank. We calculate the speed by dividing the distance traveled by the time taken.