Electromagnetic Spectrum

1. Properties of EM waves

1.1. Same velocity in vacuum (3.00 x 10^8 m/s)

1.2. Follow laws of reflection and refraction

1.3. Transfers energy, not electrical charge

1.4. Transverse waves

1.5. Follows wave formula v = fλ

2. Types of EM waves

2.1. Radio Waves (1 x 10^8 Hz)

2.1.1. Produced by electron oscillations

2.1.2. Used in telecommunications

2.2. Microwaves ( 1 x 10^10 Hz)

2.2.1. Produced by special devices E.g. Klystron

2.2.2. Used in microwave oven and satellite communication

2.3. Infrared (1 x 10^12 Hz)

2.3.1. Produced by hot objects

2.3.2. Used in thermal imaging and remote controls

2.4. Visible Light ( 5 x 10^14 Hz)

2.4.1. Red light has LARGEST wavelength, LOWEST frequency

2.4.2. Violet light has SMALLEST wavelength, HIGHEST frequency

2.4.3. Used in optical fibres and telecommunications

2.5. Ultraviolet (3 x 10^16 Hz)

2.5.1. Produced by sunlight

2.5.2. Used in sterilisation of medical instruments and suntanning

2.6. X-rays (3 x 10^18 Hz)

2.6.1. Produced by high speed collisions of electrons with metals

2.6.2. Used in airport scanners and bone imaging

2.7. Gamma rays (3 x 10^20 Hz)

2.7.1. Emitted by nuclei of radioactive atoms

2.7.2. Used in cancer treatment

3. Effects of absorption of EM radiation

3.1. Ionisation of living matter

3.1.1. Caused by UV, X-rays and γ rays

3.1.2. Damages cells and DNA

3.1.3. Causes cancers and foetus deformation

3.2. Infrared heating

3.2.1. Caused by IR radiation

3.2.2. Causes heating of cells