Characteristics of Waves

Wave Properties All transverse waves have similar shapes no matter how big they are or what medium they are traveling through. An ideal transverse wave has the shape of a sine curve, which looks like an S lying on its side.

Other Properties The highest points of a transverse wave are called crests. The lowest parts of a transverse wave are called troughs. The greatest distance that particles are displaced from their normal resting positions because of a wave is called the amplitude.

What about compressional waves? Obviously, compressional waves do not have crests and troughs. The crowded areas of a compressional wave are called compressions. The stretched-out areas are called rarefactions.

Wavelengths A wavelength measures the distance between two equivalent parts of a wave. This means from crest to crest or from trough to trough equals a wavelength.

Periods The period measures how long it takes for waves to pass by. The period is also the time required for one complete vibration of a particle in a medium.

Frequency Frequency measures the rate of vibrations. The frequency of a wave is the number of full wavelengths that pass a point in a given time interval. The unit for frequency is Hertz (Hz).

Equations Frequency-Period Equation: frequency = 1/period f = 1/T *Wave Speed Equation: wave speed = frequency x wavelength v = f x lambda

Practice 1. The average wavelength in a series of ocean waves is 15 m. A wave arrives on average of every 10 s, so the frequency is Hz. What is the speed of the waves? 2. An FM radio station broadcasts EM waves at a frequency of 9.45 x These radio waves have a wavelength of 3.17 m. What is the speed? 3. The speed of sound in air is about 340 m/s. What is the wavelength of a sound wave with a frequency of 220 Hz?