CHAPTER 13 WAVESCHAPTER 13 WAVES

WAVEWAVE• A wave is made up of periodic motion (motion A wave is made up of periodic motion (motion

which is repeated at regular intervals).which is repeated at regular intervals).

• The source of any wave is a vibration or oscillation.The source of any wave is a vibration or oscillation.

• Wave motion provides a mechanism for the Wave motion provides a mechanism for the

transfer of energy from one point to another transfer of energy from one point to another

without the physical transfer.without the physical transfer.

Wave motionWave motion

• Wave motion on a ropeWave motion on a rope

• Wave motion in a ripple tankWave motion in a ripple tank

• Wave motion in a springWave motion in a spring

Long Long slinky springLong Long slinky spring

Transverse waves are waves that travel at Transverse waves are waves that travel at right angles to the direction of vibrationsright angles to the direction of vibrations

Examples: water, light & radio waves.Examples: water, light & radio waves.

LONGITUDINAL WAVESLONGITUDINAL WAVES

• Longitudinal waves are waves that Longitudinal waves are waves that travel in the same direction in travel in the same direction in vibrations.vibrations.

• Examples, sound waves.Examples, sound waves.

•Amplitude – it is the maximum displacement of a particle from it rest position.

•Wavelength – it is the distance between two successive crests or troughs.

• x and x’ are in phase (these two points move in the same direction, have the same speed and same displacement)

Definitions of amplitude and Definitions of amplitude and wavelengthwavelength

Definitions of frequency and periodDefinitions of frequency and period

• Frequency – the frequency ( f ) of a wave is the number of crests ( or troughs ) that pass a point per second. (SI Unit Hertz – Hz)

(Frequency is the number of complete waves/cycle formed in a second.)

• Period (T) – the time taken for one complete oscillation

• Wavelength (λ) – the distance between two points in a wave that are in phase.

EQUATIONEQUATION

f

1T

λ v

f

Practice QuestionPractice Question

1. What is the wavelength of the wave motion?2. If the period of the wave shown above is 1.0 s, what is the

frequency and speed of the wave?3. Sketch the profile of the wave after 0.025 s with point Q

labeled.