Wave is a disturbance that travels through a medium or a vacuum and carries energy
Wave train or periodic wave - a succession of periodic disturbances
Examples of waves in everyday life:
Light waves enable us to see
Sound waves allow us to hear
Radio waves transmit information
Microwaves are used in cell phone communication
Microwaves are used in microwave ovens for cooking
Ultrasound and X-rays are used in medical diagnosis
Ultraviolet rays are used to sterilize medical devices
A Slinky toy can be used to observe waves
Characteristics of waves:
Frequency: number of waves produced per unit time, measured in hertz (Hz)
Period: time for one complete cycle of a wave to pass a reference point, reciprocal of frequency. as a measure of time, is expressed in units of time, usually seconds.
Wavelength: distance between two successive points in phase with each other in a wave
Speed: distance traveled by a wave per unit time
Amplitude: maximum displacement of a particle on a medium from its resting position
Transverse waves:
Particles vibrate perpendicular to the direction of wave propagation
Consist of alternating hills and valleys
Longitudinal waves:
Particles vibrate parallel to the direction of wave propagation
Wavelength is the distance between consecutive rarefactions or compressions
Body waves:
Travel through Earth's interior
Divided into Primary waves (P waves) - longitudinalSecondary waves (S waves) - tranverse
Surface waves:
Travel on the surface of Earth
Love waves move the ground from side to side
Rayleigh waves move the ground up and down
Energy transmission by waves:
Waves transfer energy without significant particle movement
Energy is proportional to the square of amplitude
Energy is proportional to the square of frequency for mechanical waves
Energy of an electromagnetic wave depends on frequency and is inversely proportional to wavelength
Intensity of a wave:
Defined as energy transported per unit area and time
Inversely proportional to the square of the distance from the source (inverse square law)
Energy Transmission by Waves:
Several factors affect the energy of a wave. Some of these factors are amplitude,frequency,wavelength, and distance.
Wave Pulse - single unrepeated disturbance
Mechanical Waves
• requires a medium to propagate. Example of a mechanical wave is a sound wave. It cannot travel in a vacuum.
Electromagnetic Waves
• Can travel in a vacuum and any medium.
• Examples are radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma rays
Transverse Wave
• the particles of the medium vibrate perpendicular to the direction of wave propagation and consist of alternating hills and valleys
Longitudinal Wave
• particles of the medium vibrate parallel to the direction of the wave propagation. In longitudinal waves, wavelength is the distance between any two consecutive rarefactions or any two consecutive compressions.