electromagnetic waves

order the EM spectrum

lower frequency, longer wavelength

1. radio waves

2. microwave

3. infrared

4. visible light

5. ultraviolet

6. x-rays

7. gamma rays

higher frequency, shorter wavelength

all EM waves are… waves

transverse

what is the speed of EM waves

all EM waves travel at the same speed of 3 × 10^8 in vacuum

equate wave speed, frequency and wavelength

v = f * wavelength

what are ionising waves and why are they dangerous

waves with higher frequencies and higher energies. they can penetrate the body deeper and remove electrons from atoms and molecules to create ions. the ions can cause harm by disrupting cell functions and even killing them

what are the 2 ways to transmit radio wave information

1. amplitude modulation (AM)

2. frequency modulation (FM)

uses for radio waves

1. radio and TV communication

2. astronomy (to deduce materials, temperatures and processes in the celestial objects, as radio waves are produced by some celestial objects)

3. radio frequency identification

uses for microwaves

1. cooking (agitate the water molecules in the food and creates friction between the molecules, thereby heating up the food)

2. radar communication

3. satellite communication eg mobile ohone networks

4. cancer treatment GPS

uses of infrared waves

1. thermal camera / imaging

2. infrared camera (take pictures without flashlights in teh dark)

3. remote control

4. intruder alarm

5. cook

6. data transfer

7. long distance optic cables

uses of visible light

1. optical fibres for telecommunications (short pulses of light)

2. photosynthesis

3. lasers for medical and industrial uses (cutting . sealing stuff)

4. taking photos

5. polymerisation

uses for UV rays

1. detection of forgery in bank notes

2. artificial suntanning

3. sterling and disinfecting equipment (killing microorganism through altering and damaging their DNA)

uses of x ray

1. analysing the structure (of a crystal)

2. airport baggage scanner

3. medical diagnosis of patients’ bones

4. checking flaws in metal

uses of gamma rays

1. killing cancer cells

2. sterilising medical equipment

3. checking flaws in metal products

name the wavelength for radio wave

10³ m

name the wavelength for microwave

10^-2m

name the wavelength for infrared waves

10^-5m

name the wavelength for visible light

0.5 × 10^-6m

name the wavelength for UV

10^-8m

name the wavelength for x-ray

10^-10m

name the wavelength for gamma ray

10^-12m

how does a x ray work in x ray imaging

as x rays pass through the human body, different body parts with different densities will absorb x rays at varying degrees (denser body parts like bones absorb x rays). lighter areas indicate that x rays were absorbed, darker areas are where x rays are not absorbed. allowing doctors to see body parts more clearly and identify any fractures or tumours or anomalies.

harmful effects of UV and how to prevent

skin cancer and premature aging

use sunscreen