3.13

Recall the detrimental effects of excessive exposure of the human body to electromagnetic waves, including:

Microwaves: internal heating of body tissue
Infrared: skin burns
Ultraviolet: damage to surface cells and blindness
Gamma rays: cancer, mutilation

3.12

Recall some of the uses of electromagnetic radiations, including:

Radio waves: broadcasting and communications
Microwaves: cooking and satellite transmissions
Infrared: heaters and night vision equipment
Visible light: optical fibres and photography
Ultraviolet: fluorescent lamps
X-rays: observing the internal structure of objects and materials and medical applications
Gamma rays: sterilising food and medical equipment

(Source: http://static.newworldencyclopedia.org/thumb/9/99/EM_Spectrum3-new.jpg/500px-EM_Spectrum3-new.jpg)

3.6

Understand, and use the relationship between frequency and time period:



f = 1/T
Frequency (Hz) = 1/Time period (s)

3.5

3.5 - Understand the relationship between the speed, frequency and wavelength of a wave:

v = f x λ

Which is

Wave speed (m/s) = frequency (Hz) x wavelength (unit of length)