8.P.3A.6 Obtain and communicate information about how various instruments are used to extend human senses by transmitting and detecting waves (such as radio, television, cell phones, and wireless computer networks) to exemplify how technological advancements and designs meet human needs.
THE ELECTROMAGNETIC SPECTRUM: REWIND……
The electromagnetic spectrum depicts the range of all possible frequencies of electromagnetic radiation. Radio waves are classed as ______frequency, ______-wavelength and ______energy waves, and gamma rays are classed as ______- frequency, ______-wavelength and ______energy waves.
n The ones humans can see are called ______, a small part of the whole spectrum.
n Also remember that wavelengths or opposite from frequency. As wavelength ______, frequency ______.
USES OF ELECTROMAGNETIC WAVES IN TECHNOLOGY
Signals that humans cannot sense directly can be detected through technological advances and designs. Radios, televisions, cell phones and wireless computer networks are examples of such technologies that are beneficial to humans by receiving and transmitting signals through radio waves.
These signals are transmitted through a ______(which can include the air or fiber optic cables) and captured by the device.
The ______the frequency of the radio wave, the ______information it can carry. For example, the radio waves transmitted and received by wireless computer networks are at much higher frequencies than those used by other devices.
Radios, televisions, and cell phones ______detect these waves that carry the enormous amounts of information required for ______usage. The signals sent and received by radios, televisions, cell phones and wireless networks are often ______. When in digitized form, information can be ______, ______for future recovery, and ______over long distances without substantial ______.
1. Radio Waves (communications---radio; tv; wireless computer)
n If you look at the diagram of the electromagnetic spectrum above, you will notice that radio waves have the ______wavelengths of the spectrum. Antennae of a radio detects radio waves. These waves must be turned into ______waves by a radio before you can hear them.
The speed of radio waves is approximately 185 miles per second, which is also the speed of ______. Radio waves are detected using ______that receive these signals in an ______, and then the radio frequencies are modulated (adjusted) through ______(a device used to store an electric charge), before emerging as sound in a speaker.
Benefits: Radio waves are used to ______signals through the ______, with the main benefit being that the only equipment necessary is a transmitter and receiver. There are ______cables to string or holes to dig as the waves are simply transmitted from one place to another. ______communicate by using radio waves to send signals to the antennas on the Earth. The ______then capture those signals and process the information coming from those signals.
Dangers: In large doses, radio waves, also known as radio frequencies, can disrupt biological functions and break down tissue.
2. Microwaves (cellphone service and microwaves for cooking)
n Microwaves are sometimes considered to be very short radio waves (higher frequency and higher-energy than radio waves).
Some important properties of microwaves are:
1. They are reflected by metal surfaces. 2. They pass through glass and plastics.
3. They pass through the atmosphere. 4. They are absorbed by water molecules.
Benefits: ______and ______use microwaves between 1 cm & 20 cm for communication.
n In ______, a vibrating electric field causes water molecules to rotate billions of times per second causing friction, creating TE which ______the food.
Dangers: Microwaves are absorbed by living tissue. ______heating will damage or ______cells.
3. Infrared Radiation (remote controls, toasters)
· Any object that radiates ______, radiates Infrared Radiation
· Infrared Radiation is ______by all materials and causes heating
· Used daily in ______, to read CD-ROMs
· It is used for ______and ______because Infrared Radiation is visible in daytime or night-time
· Dangers: damage to cells (burns)
4. Ultraviolet
· Danger: over-exposure to ultraviolet rays damages surface cells and eyes and can cause ______. Have enough energy to enter skin cells.
· Benefit: UV synthesizes vitamin ______in skin.
5. X-rays
· X-rays detect bone breaks; they pass through ______but not dense material like ______
· Dangers: X-rays damage cells and cause cancers.
6. Gamma Rays
· Gamma Rays ______and ______cancers
· Kill bacteria
· In ______doses, gamma can kill ______cells and cause cancers