Chapter 13 Waves Flashcards
What is a wave?
A wave is made up of particles in periodic motion. It is a disturbance that transfers energy from one place to another, but does not transfer matter during the energy transfer.
Define periodic motion
Motion repeated at regular intervals
Define oscillation/ vibration
One complete cycle of periodic motion
Define how the particles of longitudinal waves travel.
Particles of a longitudinal wave vibrate parallel to the direction of travel of the wave motion.
Define how the particles of a transverse wave travel.
Particles of a transverse wave vibrate perpendicular to the direction of travel of the wave motion.
Define compression.
Compression is the part where particles are closest to one another and where air pressure is slightly higher than the surrounding air pressure.
Define rarefaction.
Rarefaction is the part where particles are spread apart and where air pressure is slightly lower than the surrounding air pressure.
Define crests and troughs.
Crests are the highest points and troughs are the lowest points of a transverse wave.
Define amplitude of a wave and state its SI unit.
The amplitude A of a wave is the maximum displacement of a point from the equilibrium position/ its rest position. The SI unit is metre (m).
Define the wavelength of a wave and state its SI unit.
The wavelength of a wave is the shortest distance between any two points that are in phase/ distance between 2 successive crests or troughs. The SI unit is metre (m).
Define period of a wave and state its SI unit.
The period T of a wave is the time taken to produce one complete wave/ time taken for any point of the wave to move a distance of one wavelength. The SI unit is second (s).
Define frequency of a wave and state its SI unit.
The frequency f of a wave is the number of complete waves produced per second/ the number of crests/ troughs that pass a point per second. The SI unit is hertz (Hz).
Explain what it means for the points of a wave to be ‘in phase.’
Points along a wave are in phase if they have the same direction of motion, same speed and same displacement from their rest position.
Define wave speed and state its SI unit.
Wave speed v is the distance travelled by a wave per second. The SI unit is metre per second (m s^-1)
How are frequency and period related?
They are related by the equation f = 1/T