Year 9 – Physical Science Year 9 – Physical Science Characteristics of waves

Year 9 – Physical Science Year 9 – Physical Science The Nature of Waves A wave is a repeating disturbance or movement that transfers energy through matter or space

Year 9 – Physical Science Year 9 – Physical Science Types of Waves Some kinds of ENERGY travel in a wave Do not need a medium to travel through Needs a medium to travel through Longitudinal Waves Transverse Waves Electromagnetic Waves Mechanical Waves

Year 9 – Physical Science Year 9 – Physical Science What are the two kinds of mechanical waves? (a) Transverse Waves In a transverse wave the matter in the wave moves up and down at a right angle to the direction of the wave

Year 9 – Physical Science Year 9 – Physical Science Example of a transverse wave: Light also travels in transverse waves

Year 9 – Physical Science Year 9 – Physical Science (b) Longitudinal Waves (Compression Waves) In a longitudinal wave the matter in the wave moves back and forth parallel to the direction of the wave

Year 9 – Physical Science Year 9 – Physical Science Sound waves are an example of compressional waves Sound travels as vibrations moving through the air as a compressional wave. Sound travels through air, but travels through other materials as well. Whales communicate through long distances by producing sounds under water.

Year 9 – Physical Science Year 9 – Physical Science Longitudinal (compressional) wave e.g. sound Transverse wave (e.g. light)

Year 9 – Physical Science Year 9 – Physical Science

What are the parts of a wave? Transverse wave The crest is the highest point on a transverse wave. The trough is the lowest point on a transverse wave. The rest position of the wave is called the node or nodal line. The wavelength is the distance from one point on the wave to the next corresponding adjacent point.

Year 9 – Physical Science Year 9 – Physical Science The amplitude of a transverse wave is determined by the height of the crest or depth of the trough

Year 9 – Physical Science Year 9 – Physical Science Parts of a Longitudinal wave On a longitudinal wave the area squeezed together is called the compression. The areas spread out are called the rarefaction. The wavelength is the distance from the center of one compression to the center of the next compression.

Year 9 – Physical Science Year 9 – Physical Science

Sketching Waves What is the (a) amplitude of this wave, (b) wavelength of this wave, (c) frequency of this wave? Wavelength Amplitude