p5.2 electromagnetic spectrum

Question 1

what is the electro-magnetic spectrum

Answer 1

this is a range of wave frequencies.

Question 2

in order of low to high name all the things on the spectrum

Answer 2

radio waves, microwaves ultraviolet, visible light, infrared, xrays, gamma waves

Question 3

what are electromagneic waves

Answer 3

these are oscillating electric and magnetic fields. the fields vibrate at 90 degrees to the direction of the wave

Question 4

how fast do electromagnetic waves travel in a vacuum

Answer 4

they travel at the speed of light which is 3.0 X 10^8

per second

Question 5

what are sources in terms of electromagnetic waves

Answer 5

these are what emit the waves eg the sun

Question 6

what are absorbers

Answer 6

these are what the energy is transferred into. eg food in a microwave

Question 7

how are these waves produced and detected

Answer 7

an oscillating potential difference across a wire causes electrons to move. this changes the surrounding electromagnetic fields. this is the radio waves. when the waves come in contact with another wire or aerial the electrons being to move at the same frequency. this would then travel down the wire and be translated by a computer

Question 8

give examples of how electromagnetic waves are used

Answer 8

in tv remotes, phone communicate with satellites, tv and radio stations, used to heat food, lasers that read optical disks, ultraviolet lights are used at crime scenes and used to treat cancer by killing it.

Question 9

which waves are dangerous and why

Answer 9

UV rays can be dangerous because they can damage the DNA of the skin causing mutations. x-rays and gamma rays can also cause cancer.

Question 10

how is infrared used for medical purposes

Answer 10

it is used for thermal imaging. pixels inside a charge coupled device detects infrared waves. the hotter something is the more waves the emit. damaged and injured body parts are hotter than normal.

Question 11

how are x-rays used for medical purposes

Answer 11

structures such as bone absorb x-rays. the photographic film darkens when this happens. this shows us clearly the inside of the person. some cameras show different camera based on how much is absorbed. x-rays can be used in CT scans and for 3D imaging

Question 12

how are gamma rays used for medical purposes

Answer 12

a radio active substance called a tracer that emits gamma rays is injected into a person. this tracer will travel to the kidney. using special cameras the spike in gamma radiation is recorded and used to check the kidney