1. Use the wave model to explain how technologies transfer information (in communications)
Many of today’s communications systems transfer information and energy using waves.
1.1 Describe the energy transformation required in one of mobile telephone, fax, modem, radio and television (see dot point 3.9 for more details)
Mobile phone: Sound energy (speak into mouth piece, source) is converted to electromagnetic energy (microwaves – high frequency radio waves) and is transferred from source to receiver via radio transmitters. The electromagnetic energy is then transformed back into sound energy by the receiver. mobile phone-how it works;
More details are covered in section 3.9
2. Types of waves
Energy is transferred by wave motion in one dimension, two dimensions and three dimensions
Waves can be categorized as :
- Mechanical waves, consisting of vibrating particles with energy, which require a medium for propagation. Mechanical waves can be transverse (waves in a ropes, strings, slinky coils), sound (longitudinal), torsion (twisted waves of ropes), surface waves (secondary seismic waves produced by earthquakes). Mechanical waves such as ocean waves can be a combination of transverse and longitudinal waves.
- Electromagnetic waves, which do not require a medium for propagation. (all waves from the electromagnetic spectrum
waves – earthquakes
2. Waves: Longitudinal and Transverse waves
animations – longitudinal and transverse waves
Experiment 1: video: Slinky coil to create longitudinal waves
Experiment 2: Video: Slinky coil to create transverse waves.
websites for longitudinal and transverse waves:
waves animations -shows the positons of the wave particles after a certain period of time.
Questions on waves (physics classroom)
Oscilloscope (CRO simulation) – change frequency and amplitude
videos – sound waves -how it travels to the ear drum.
Questions on wavelength, period, frequency
Definition of wavelength, period, frequency, amplitude. (bbc)
video (bbc) changing wavelength, etc
Global Position System (GPS)
2.1 Longitudinal waves:
1. Sound is caused by vibrations (animation) of the particles in the medium.
2. Sound waves is a series of compressions and rarefactions.(video links)
Longitudinal waves animation video
other links to loudness and frequency
Displaying sound waves on oscilloscope.
Superpostion and interference of waves
Wave interference occurs when two or more waves act simultaneously on a medium.Whenever two or more waves pass through each other, the resulting disturbance at a given point in the medium may usually be found by adding the individual displacements that each wave would have caused. (Principle of Superposition)Constructive interference occurs when the resulting disturbance is larger than the individual disturbances which created it.When the resultant displacement is smaller than the individual displacements, destructive interference has occurred.
constructive and destructive interference due to superposition of waves.
Quiz- physics classroom on constructive and destructive interference.
8.2.3 Electromagnetic Radiation
What is electromagnetic waves?
All eLectromagnetic waves travels at 300 million m/s through the space. Different electromagnetic waves have different wavelengths. Find out more about the different types of electromagnetic waves.
Electromagnetic Spectrum introduction (nasa) (5.20 mins)
Reflection of light in a concave mirror
Images in a plane mirror
refraction through different medium
Diffraction (tutor vista)