sonar: sound navigation and ranging ships use reflected sound waves to locate objects underwater...
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Sonar: SOund NAvigation and Ranging
Ships use reflected sound waves to locate objects underwater
Echolocation: Bats use reflected sound waves to navigate and hunt in the dark
Ultrasound: reflections of ultrasonic sound waves off of the soft tissues of the body are used to create an image
Can also use ultrasound to watch a person’s heart while it’s beating, to examine tumors, and to break up kidney stones.
Electromagnetic waves
Recall that both electrical charges and magnets have fields around them.
An electromagnetic wave is a double transverse wave that consists of both an electric and a magnetic field wave
Electromagnetic waves are transverse waves because the electric and magnetic fields vibrate in a direction perpendicular to the direction of travel.
Like all transverse waves, electromagnetic waves can be described in terms of their energy content, wavelength, frequency and wave speed.
Radiant energy: the energy content of an EM wave
Wave speed: the speed of EM waves depends upon the medium they’re travelling through. While they do not require matter to propagate, they do interact with matter which slows them down.
Vacuum: 300,000 km/s Water: 226, 000 km/s
Diamond: 124,000 km/s
http://lectureonline.cl.msu.edu/~mmp/kap28/PhotoEffect/photo.htm
Photoelectric Effect
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Na metal
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‘Particles’ of light are called photons
The light given off by elements when burning produces a line spectrum that can be used to identify the element.
Opaque: will not transmit light
Translucent: will transmit some light
Transparent: transmits almost all of the light
Transmission of light
Reflection of Light
Diffuse reflectionRegular reflection
Smooth surfaces will reflect the incident light waves in a single reflected beam.Ex: Driving at night on a WET road
Rough surfaces reflect the incident waves in many different directions.Ex. Driving at night on a DRY road
Refraction
Index of refraction: a number that indicates how much the light will bend when it goes from air to the new medium.
The higher the index of refraction, the greater the refraction angle
Prism: A prism separates the incident beam by wavelength.
The longest wavelengths (red) are refracted the least.
The shortest wavelengths (blue/violet) are refracted the most.