Radio waves, microwaves, infrared and visible light can all be used for communication.
Radio waves – are used to transmit television and radio programs.
Microwaves – are used to transmit satellite television and for mobile phones.
Infrared – is used to transmit information from remote controls.
Visible light – is used in photography.
Reflection – the angle of incidence is equal to the angle of reflection.
Sound waves are longitudinal waves. They can be reflected by surfaces, these reflections are called echoes.
Frequency is the number of waves per second, it is measured in hertz (Hz). The pitch of a sound is determined by its frequency.
High frequency sound waves are high pitch sounds.
Low Frequency sound waves are low pitch sounds.