National 5 Waves Flashcards
Factual Recall
What do all waves wave transfer?
All wave transfer Energy
Explain the difference between a transverse and longitudinal wave.
In a transverse wave the particles of the medium oscillate at right angles to the direction of energy transfer.
In a longitudinal wave the particles of the medium medium oscillate parallel to the direction of energy transfer.
Give and example of a longitudinal and a transverse and a wave.
Longitudinal: Sound
Transverse: Water, Light, Radio Waves, All Electromagnetic Waves
Define Frequency
Frequency (f) is the number of waves produced (or passing a point) per second.
It is measured in Hertz (Hz).
1.4 Define Wavelength
Wavelength (greek letter lambda λ) is the length of one complete wave, often measured between successive crests or troughs.
It is measured in metres (m).
For example, A in the image.
Define the Period of a wave.
The Period (T) of a wave is the time taken to produce for one whole wave.
(One whole crest and one whole trough).
It is measured in seconds (s).
Define the Amplitude of a wave.
Amplitude is the height of a wave from the line of zero disturbance to the top of a crest, or from the line of zero disturbance to the bottom of a trough.
It is measured in metres (m).
For example, D in the attached image.
Define the Speed (v) of a wave.
The Speed (v) is the distance travelled per unit of time by a wavefront.
It is measured in metres per second (ms-1).
Define a Crest
A Crest is the highest point of a wave.
For example, B in the attached image.
Define a Trough
A Trough is the lowest point of a wave.
For example, C in the attached image.
Which feature of a wave is measure of its energy?
A Wavelength
B Frequency
C Speed
D Amplitude
E Period
D Amplitude
The greater the amplitude of a wave, the greater its energy.
f = 1/T
(Define symbols and units)
f - frequency (Hz)
T - period (s)
Example
A bat emits ultrasounds with a period of 23 µs. Calculate the frequency of the ultrasound.
T = 23 µs = 23 x 10<sup>-6</sup> s f = ?
f = 1/T f = 1/23 x 10<sup>-6</sup> f = 4.35 x 10<sup>4</sup> Hz
f = N/t
(Define symbols and units)
f - frequency (Hz)
N - Number of waves (no units)
t - time (s)
Example
A siren produces 26,400 waves per minute.
Calculate their frequency.
N = 26,400 t = 1 min = 60 s f = ?
f = N/t f = 26,400/60 f = 440 Hz