Waves Flashcards
Wave : definition
Waves transfer energy from one place to another
Transverse waves
Particles of the medium (air/water) vibrate (move to and fro) at right angles to the direction of travel of the wave
particles of the medium vibrate in the same direction as - ie parallel to - the direction of travel of the wave.
In longitudinal waves the particles of the medium vibrate in the same direction as - ie parallel to - the direction of travel of the wave.
Crest
High parts of a wave
Troughs
Low parts of waves
Wavelength
The distance between any two successive peaks (or between any two successive troughs)
Amplitude
the height of a crest above the average level (or the depth of a trough below it)
Frequency
the number of waves per second - or the number of cycles per second or the number of oscillations per second.
What longitudinal waves have instead of peaks and troughs?
Compressions and rarefactions
Wave equation
Speed = frequency x wavelength
Frequency measurement
Hz
Wavelength measurement
M
What is used to change sound waves into electrical signals?
Microphone
What is the loudness of a sound measured by?
Itβs amplitude
What is the pitch of a sound measured by?
Its frequency
Relationship between angle of incidence and angle of reflection
I = r
speed of waves in shallow water
Slow
Wavelength of waves in shallow water
Shorter
Frequency of waves in shallow water
The same
Why does the speed of waves change in shallow water?
Cannot keep up increase friction in shallow water
Echo
A sound wave is reflected off a hard surface
How can we calculate how far away object are
Using echoes and the speed of sound
Radar
An object detection system which uses radio waves to determine the range, altitude, direction or speed of objects
How does radar work?
Radar dish or antenna transmits, pulses, radio, waves, or microwaves, which bounces off any object in their path
Object returns, tiny part of waves energy to dash/antenna, which is usually located at the same site as transmitter οΏΌ
Ultrasound
Signs which have a frequency above the range of human hearing
Ultrasound
Ultrasonic sounds
Ultrasound frequency
Above 20 kHz = 20,000 Hz
Uses of ultrasound
- medicine π©ββοΈ
- Industrial cleaning π§Ό
- sonar ππ β΄οΈ
Sonar uses
- Depth of water π π
- detect shoals of fish π
- Warships use this to detect submarines β΄οΈ
Medical uses of ultrasound
- Ultrasonic scans
- Break up kidney stones
- Physiotherapy
Ultrasonic scans
- Build a picture of unborn baby in the womb
- Safer than x-rays, x-rays damage body cells of mother and baby
Industrial cleaning ultrasound
Some industrial processes make use of ultrasound dust is shake it off by vibrations
What does sonar stand for?
SOund Navigation and Ranging
Electromagnetic spectrum
Family of waves, which have several properties in common
Similarities of electromagnetic spectrum waves
- Can travel through a vacuum
- Travel through a vacuum at the same speed (speed of light, 300,000,000 m/s)
- Are all electromagnetic waves
Gamma rays
Short wave lengths with high frequencies
Radio waves
Long wavelength with low frequencies
What increases as wave frequency increases?
Energy that waves carry
What is part of the electromagnetic spectrum?
The visible spectrum
High frequency radiation, danger
Causes more damage to living tissues
Danger of microwaves
Can cause internal heating of body tissues
Infrared radiation dangers
Felt as heat and can cause skin burns
Certain wavelengths of ultraviolet light, dangers
Can damage skin cells and lead to skin cancer
Intense visible light, dangers
Can damage eyes
Dangers of x-rays and gamma rays
Damage cells which may lead to cancer 10 to damage the DNA in cells
Dangers of large doses of radio waves
- Believed to cause cancer, leukaemia, and other disorders
- Some claim very low frequency radio waves from overhead power cables near homes has affected health. - not been reliably provenοΏΌ
