Progressive Waves
Applied Science: BTEC Level 3 National Extended Diploma, topic 1.6.1
Waves - Examples
Waves transfer energy from one place to another without transferring matter. Wave motion (the movement of waves) can be shown by the vibrations of a spring or by water waves.
Springs - transverse waves
- Hold one end of a horizontal spring in a fixed position and move the other end of the spring up and down.
- We can observe a wave moving from the end we are holding towards the fixed end of the spring.
Water
- When a wave travels along the surface of water, a cork floating on the surface of the water will only move up and down as the wave passes.
Frequency and Period
All waves have a frequency and a period of oscillation.
Frequency
- Frequency is the number of oscillations (vibrations) per second.
- Frequency = number of oscillations ÷ time
- The frequency is equal to 1 divided by the period.
- Frequency = 1 ÷ period
- Frequency is measured in Hertz (Hz).
Periodic time
- The periodic time of a wave is the time taken to complete one oscillation (vibration).
- It is equal to 1 divided by the frequency.
- Periodic time = 1 ÷ frequency
- The periodic time of a wave is measured in seconds.
Measuring Waves
Two important measurements for waves are amplitude and wavelength. Both are measured in metres.
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Amplitude
- The amplitude of a wave is the largest distance that a point on the wave moves from its rest position.
- For example, the distance from the rest position of a wave to the top of a wave’s peak.
Transverse
- The wavelength is the distance between two adjacent wavefronts. For transverse waves, this is the distance between two peaks of adjacent waves.
Test yourself on Progressive Waves
How will a cork behave in water when waves are present?
What do waves transfer?
Spring Vibrations Experiment
What is the unit of frequency for a wave?
What is the frequency of a wave that has oscillated (vibrated) 30 times in 6 seconds?