Environment

For certain animals sound is not only a way to communicate but also a way to maneuver and locate food sources. A bat navigate by emitting high-pitched sound waves and listening for the reflection of those waves off of near by objects to determine their distance. Their hearing is so well adapted that they can detect the presence of an insect up to 10 meters away.

Sound is a Longitudinal wavelength. The way we perceive a sound depends on its wavelength, frequency and amplitude. High frequency sound waves give off a high pitch noise, while lower frequencies give off a lower pitched noise

Environment Cont. Do you ever wonder why the grass

is green, or why the sky is blue?

The answer is visible light. Visible light is a type of electromagnetic wavelengths range from red light at about 700 nanometers down to violet at about 400 nanometers So as you can see from the chart to the right , green leaves reflect a higher frequency of visible light than that of a red petal.

Health

An electromagnetic wave that most of us are familiar with is the X-ray. As seen on the previous slide X-ray's wavelength is about 100 nanometers down to 0.1 nanometers (smaller than a single atom). These high frequency waves can penetrate several centimeters into most solid matter are absorbed to different degrees by all kinds of materials.

X-rays are often used to prevent harmful materials from entering public places such as airports.

Health Cont.

0

Column 1

Column 2

Column 3

Medical X-ray machines are like giant light bulbs in a glass vacuum tube. One end of the tube is a tungsten filament that is heated to a very high temperature by an electrical current at the other end is a polished metal plate. The X-ray is then produced by applying high voltage negative current on the filament and a positive current over the polished metal plate. This causes electrons to stream across the filament and smash into the plate at high velocity creating what you see as a medical x-ray.

Geology

Once a wave has been generated its movement is independent from its origin.

In the study of the earth we can see how waves of energy generated by the movement of tectonic plates disperses and often causes natural disasters.

Geology Cont. The consequence of waves' movement being

independent from its source is called The Doppler Effect; A change in the observed frequency of a wave, as of sound or light, occurring when the source and observer are in motion relative to each other, with the frequency increasing when the source and observer approach each other and decreasing when they move apart. The motion of the source causes a real shift in frequency of the wave, while the motion of the observer produces only an apparent shift in frequency. Also called Doppler shift.

Meteorologists use Doppler radar to measure wind speed and direction during the approach of the storms to help predict the weather.

Doppler radar works by sending out microwaves through a central antennae When these microwaves encounter different types of precipitation they reflect back to the antennae in frequencies unique to that type of precipitation. Doppler radar can detect precipitation and wind speed because it not only measures the frequency of the returning waves but also their intensity.