This document defines key terms related to waves. It discusses periodic waves, which repeat at regular intervals, and how one oscillation is one complete periodic motion from a starting point back to that starting point. It also defines key wave characteristics like wavelength, amplitude, period, frequency, wave speed, wave fronts, and describes transverse and longitudinal wave motion. Crests and troughs are defined for transverse waves, while compressions and rarefactions are defined for longitudinal waves.

1. Chapter 11 Waves

2. WAVES TERMINOLOGY

3. Periodic waves If the disturbance to the medium happens only once , a single wave pulse is produced. If the disturbance to the medium happens in regular repetitions , a periodic wave is produced.

4. Periodic waves The particles of the medium of a periodic wave are exhibiting periodic motion . Periodic motion is motion repeated at regular intervals .

5. Periodic waves – one oscillation One complete periodic motion is known as an oscillation . One oscillation is completed when the pendulum bob moves from A to B, and then back again to A.

6. Periodic waves – one oscillation Starting position Direction of wave Transverse wave 1 2 3 4 Starting position Direction of wave Longitudinal wave 1 2 3 4

7. Terms to describe wave motion Crest and troughs : The highest and lowest points of a transverse wave, respectively. Compressions and rarefactions : The regions of a longitudinal wave where the wave particles are closest together and furthest apart, respectively

8. Terms to describe wave motion Phase : Any two points are said to be in phase when they move in the same direction and have the same speed and the same displacement from the rest position .

9. Terms to describe wave motion Wavelength ( )(m): The shortest distance between any two points that are in phase. Amplitude ( )(m): The maximum displacement from the rest or centre position.

10. Terms to describe wave motion Period ( )(s): The time taken for one point on the wave to make one oscillation. This is also the time taken to produce one complete wave. Period is the time taken for one point to complete one oscillation (Motion 1 to 4). Starting position Direction of wave Transverse wave 1 2 3 4 Starting position Direction of wave Longitudinal wave 1 2 3 4

11. Terms to describe wave motion Frequency ( )(Hz): Number of complete waves produced per second. Period of the wave

12. Terms to describe wave motion Wave speed ( )(ms -1 ): How quickly the wave propagates. Wave speed Frequency of the wave Wavelength of the wave

13. Terms to describe wave motion Wave front : An imaginary line on a wave that joins all points that are in the same phase. Usually drawn by joining all the wave crests.

14. Terms to describe wave motion Direction of wave motion. Compression Rarefaction Crest Trough 1 wavelength 1 wavelength 1 wavelength 1 wavelength 1 wavelength Amplitude

15. Terms to describe wave motion Direction of wave Transverse wave A B Points A and B are in phase. They are 1 wavelength apart. Amplitude Amplitude Amplitude

16. Terms to describe wave motion Starting position Direction of wave Longitudinal wave 1 2 3 4 Amplitude Amplitude