SSA Review 7 – Energy and Waves

What is electromagnetic radiation? *the energy that is moved by E.M. waves *it travels through empty space, air, and water and moves at the speed of light (186,000/mps)

3 – What is the electromagnetic spectrum? *the range of energy composing E.M. waves *every wavelength travels at the same speed

A) Radio waves - has the longest wavelength and lowest energy http://missionscience.nasa.gov/ems/emsVideo_02radiowaves.html *Examples of how this energy is used: Broadcasting radio and TV programming Used to pick up transmissions from outer space

B) Microwaves *Shorter than radio waves, but has more energy http://missionscience.nasa.gov/ems/emsVideo_03microwaves.html *Examples of how this energy is used: Cooks food faster than conventional ovens Radar to detect speed and movement Cellular signal transmissions (cell phones, text messages, photos, etc.), able to penetrate through clouds and haze in the atmosphere

C) Infrared rays *waves that are felt as heat http://missionscience.nasa.gov/ems/emsVideo_04infraredwaves.html *Examples of how this energy is used: Night vision goggles used to detect people in the dark Animals use this to detect warm-blooded prey Remote controls use this to change channels/settings Used to detect stars too far away to be seen

D) Visible light *The only energy that can be seen by our eyes *the smallest part of the E.M. spectrum http://missionscience.nasa.gov/ems/emsVideo_05visiblelight.html *Examples of how this energy is used: - Used by light bulbs to provide light - Used to view objects in space through telescopes

E) Ultraviolet (UV) rays *waves shorter than, but more energy than visible light *most of these waves are blocked by the ozone layer http://missionscience.nasa.gov/ems/emsVideo_06ultravioletwaves.html *Examples of how this energy is used: - Our bodies need it to produce Vitamin D (good for skin) *too much can cause skin damage Used in fluorescent lighting Used in dental and medical practices to kill bacteria

F) X-rays *Small, but very high energy waves that can penetrate most matter http://missionscience.nasa.gov/ems/emsVideo_07xrays.html *Examples of how this energy is used: Used to produce images of bones, teeth, etc. Used in scanners to detect a variety of hidden objects Used in equipment that can detect cracks and other deficiencies in objects or structures Too much exposure can cause cancer to humans

G) Gamma rays *has the shortest wavelength, but the most energy -the most penetrable of all the E.M. waves -produced from nuclear explosions & radioactive atoms http://missionscience.nasa.gov/ems/emsVideo_08gammarays.html *Examples of how this energy is used: Used medically to kill cancerous cells (too much can cause cancer, though) Used to sterilize medical equipment

Properties of waves *Crest – highest point of a wave *Trough – lowest point of a wave

How do the different waves compare? *Each part of the wave has different wavelengths (the distance between one crest to another)

*every wavelength travels at the same speed *Radio waves are the longest, Gamma rays the shortest *every wavelength travels at the same speed

*The shorter the wave, the faster the frequency **Frequency – the rate the waves travel through a set distance *The longer the wave, the slower the frequency *The shorter the wave, the faster the frequency

**As the wavelength decreases, the energy of the wave increases.

https://www.youtube.com/watch?v=iX8PRv_Mj18

Light Waves 1 – Light moves in a straight line unless it interacts with matter.

2 – Light will bounce off a shiny object and change directions. * This is reflection

3 – Light can bend through an object that it passes through *This is refraction. Why? Light travels slower through another medium than it does through air

4 – Light can be engulfed by an object and stop moving 4 – Light can be engulfed by an object and stop moving *This is absorption **Darker colored objects absorb more light energy than other colors

5 – Light passes through an object *This is transmission

Light Waves

Sound Waves SOUND WAVES LIGHT WAVES Velocity in Air Form Transmitting Medium Relation of Transmitting Medium to Velocity Sensations Produced Variations in Sensations Produced 1,100 feet per second Longitudinal All substances The denser the medium, the greater the speed Hearing Low frequency, low note High frequency, high note 186,000 miles per second Transverse Empty space and all substances except opaque The denser the medium, the slower the speed Seeing Low frequency, red color High frequency, ultraviolet color

Sound Waves *Moves slower than light waves http://www.acs.psu.edu/drussell/Demos/waves/wavemotion.html Sound Waves *Moves slower than light waves *Speed up when moving through any medium (solid, liquid, or gas) *Does not move through empty space