p5.2

Question 1

longest wavelength EM wave

Answer 1

radio waves

Question 2

highest frequency EM wave

Answer 2

gamma rays

Question 3

how fast are all EM waves

Answer 3

3x 10 (power of 8)

Question 4

how to produce and detect radio waves

Answer 4

• oscillating p.d across wire produces a changing electric and magnetic field
• emits radio waves
• detected by an aerial, fields meet together

Question 5

EM Waves used for communication

Answer 5

• microwaves (phone , satellites and wifi systems)
• radio waves (radio stations)
• infrared waves (remote controls )
• visible light ( flashing morse code , ships)

Question 6

infrared uses

Answer 6

communication in remotes
cooking food, by transferring energy to a thermal store
medical imaging

Question 7

ultraviolet light uses

Answer 7

• produce vitamin D
• detect bodily fluid for forensic scientists

Question 8

what EM waves damage cells?

Answer 8

ultra violet - kills bacteria and sterilises water (can damage DNA, IF EXPOSED TO EYES develop cataracts)
X-rays- kill skin cancer and other cancer cells (cause cancer)
gamma rays- kill cancer cells and kill bacteria (and other bodily cells)

Question 9

how infrared waves are used for medical imaging

Answer 9

• thermal imaging camera (produced THERMOGRAM)
• pixels in à CCD absorb infrared to produce an image
• skin will emit more radiation if there is an injury or infection
• also used to show flow blood vessels

Question 10

how X-rays are used in imaging

Answer 10

-bones absorb x-rays , not muscle or soft tissue
- CCD used to detect x-rays
- colours show difference in intensity due to densities of bones

Question 11

How gamma rays used for imaging

Answer 11

• used as tracers
• patient injected with radioactive substance that emits gamma rays (tracer)
• kidney absorbs tracer
• tracers also used to find leaks in underground pipes