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.

A repeating movement or disturbance that transfers energy... …through matter …or through space

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

R O Y G B V (I) Wavelength and Frequency of Visible light

Visible light is just a small portion of the EM spectrum

Wave nature of light

Photoelectric Effect e e e e Na metal V ‘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.

Chapter 13: Light

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.