Waves Flashcards
How can waves be measured?
Amplitude
Wave length
Frequency
What is a wave?
Waves are vibrations that transfer energy from place to place without matter (solid, liquid or gas) being transferred.
What waves can travel through a substance (solid liquid gas)?
Sound waves and seismic waves
What kind of waves can travel through empty space?
Visible light, infrared rays, microwaves and other types of electromagnetic radiation
What are the characteristics of a transverse wave?
In transverse waves, the oscillations (vibrations) are at right angles to the direction of travel and energy transfer
Light and other types of electromagnetic radiation are transverse waves. All types of electromagnetic waves travel at the same speed through a vacuum, such as through space.
What characteristics are in a longitudinal wave?
In longitudinal waves, the oscillations are along the same direction as the direction of travel and energy transfer.
Sound waves and waves in a stretched spring are longitudinal waves. P waves (relatively fast moving longitudinal seismic waves that travel through liquids and solids) are also longitudinal waves.
Longitudinal waves show area of compression and rarefaction. In the animation, the areas of compression are where the parts of the spring are close together, while the areas of rarefaction are where they are far apart.
How do you calculate wave length?
v = f × λ
v is the wave speed in metres per second, m/s
f is the frequency in hertz, Hz
λ (lambda) is the wavelength in metres, m.
What is amplitude?
The amplitude of a wave is its maximum disturbance from its undisturbed position. Take care: the amplitude is not the distance between the top and bottom of a wave.
What is the wavelength?
The wavelength of a wave is the distance between a point on one wave and the same point on the next wave. It is often easiest to measure this from the crest of one wave to the crest of the next wave, but it doesn’t matter where as long as it is the same point in each wave.
What is frequency?
The frequency of a wave is the number of waves produced by a source each second. It is also the number of waves that pass a certain point each second.
What is refraction?
Sound waves and light waves change speed when they pass across the boundary between two substances with different densities, such as air and glass. This causes them to change direction and this effect is called refraction.
What is diffraction?
When waves meet a gap in a barrier, they carry on through the gap. However, the waves spread out to some extent into the area beyond the gap. This is called diffraction.
What is the electromagnetic spectrum?
The electromagnetic spectrum is a continuous range of wavelengths. The types of radiation that occur in different parts of the spectrum have different uses and dangers, which depend on their wavelength and frequency
What are radio waves?
Radio waves are used to transmit television and radio programmes. Television uses higher frequencies than radio. Diffraction allows low-frequency radio waves to be received behind hills, although repeater stations are often used to improve the quality of the signals.
What are microwaves?
Microwave radiation can also be used to transmit signals such as mobile phone calls. Microwave transmitters and receivers on buildings and masts communicate with the mobile telephones in their range.
