Which electromagnetic waves allow us to diagnose & treat cancer?
gamma rays
Which of the following EM wave is used in night vision goggles?
infrared
Which of the following is false about electromagnetic waves?
They are produced by moving charges.
They travel at different speed in vacuum depending on its wavelength.
They travel at different speed in vacuum depending on its wavelength.
- These fields are perpendicular (at right angles) to each other
EM Waves
(the vibration is perpendicular to the direction of the
wave).
transverse waves
energy and frequency is directly proportional
wavelength and frequency is inversely proportional
classification of em waves
Non-ionizing radiation
Ionizing radiation
– lower energy (radio, microwave, infrared, visible
light, some UV)
non ionizing radiation
higher energy (X-rays, gamma rays)
ionizing radiation
Application:
Communication (AM/FM
radio, TV, Wi-Fi,
Bluetooth, GPS, MRI)
Radio Waves
Discovered by Heinrich
Hertz. FM has better sound
quality than AM.
Radio waves
Application:
Cooking, radar, Wi-Fi,
mobile phones, satellite
communication
Microwaves
Cause water & fat
molecules to vibrate → heat.
Used in radar & speed guns
Microwaves
Application:
Remote controls, night
vision, thermal imaging,
medical diagnostics
IR
Discovered by William
Herschel (1800). Detects
heat. Used in DITI for
cancer detection.
Infrared
Human vision,
photography, illumination
380-780m
Visible light
ROYGBIV – Scattering causes
blue sky & red sunset.
visible light
Application: Sterilization, fluorescent
lamps, forensic work,
LASIK surgery
Discovered by Johann
Ritter.
Can cause sunburn;
UV-C is blocked by ozone
layer.
UV Rays
10–0.01 nm
Application:
Medical imaging, airport
scanners, CT scans
X rays
High penetrating power.
Dense materials (bones)
absorb more X-rays.
X rays
< 0.01 nm
Cancer treatment,
sterilizing medical tools,
radioactive tracing
gamma rays
Most energetic; emitted by
radioactive substances.
Used in Gamma Knife
radiosurgery.
gamma rays
nm to m
1 x 10^-9
m to nm
1 x10^9
