Ms. Barlow’s 8 th Grade Physical Science Class

Waves can differ in how much energy they carry and in how fast they travel. Waves also have other characteristics that make them different from each other. These characteristics can be used to describe waves.

The distance between one point on a wave and the nearest point just like it. Transverse Waves: you can measure wavelength from crest to crest. Longitudinal Waves: wavelength is the distance between two neighboring compression or two neighboring rarefactions.

Wavelength is given the symbol (Greek lambda, pronounced lam-der), and is measured in meters because it is a distance.distance

The number of wavelengths that pass a fixed point each second. Or Frequency is defined as the number of complete cycles in one second". Hertz is the unit of frequency (symbol Hz). 1 Hertz = 1 cycle per second.

You can find the frequency of transverse waves by counting the number of crests that pass by a point each second. The frequency of longitudinal waves is the number of compressions or rarefactions that pass a point every second. A frequency of 1Hz means that one wavelength passes by in 1 s.

Wavelength is related to frequency As frequency increases, wavelength decreases.

The frequency of a wave is always equal to the rate of vibration of the source that creates it.

The speed of a wave depends on the properties of the medium it is traveling through. Example: Sound waves travel faster in liquids and solids than they do in gasses. They also travel fasted in material if the temperature of the material is increased. Light waves travel more slowly in liquids and solids than they do in gases or in empty space.

Speed = wavelength x frequency V = x f What is the speed of a wave with a wavelength of 2 m and a frequency of 3 Hz?

Amplitude is related to the energy carried by a wave. The greater the wave’s amplitude is, the more energy the wave carries. Amplitude is measure differently for longitudinal and transverse waves.

The amplitude of a longitudinal wave is related to how tightly the medium is pushed together at the compressions. The denser the medium is at the compressions, the larger its amplitude is and the more energy the wave carries.

For example, it takes more energy to push the coils in a coiled spring toy tightly together than to barely move them. The closer the coils are in a compression, the farther apart they are in a rarefaction so the less dense the medium is at the rarefactions, the more energy the wave carries.

Amplitude of transverse waves How can you tell the difference between a transverse wave that carries a lot of energy from one that carries little energy? If you’ve ever been knocked over by an ocean wave, you know that the higher the wave, the more energy it carries. So, a tall ocean wave has a greater amplitude than a short ocean wave does.

The amplitude of any transverse wave is the distance from the crest or trough of the wave to the rest position of the medium.