Waves
Waves Basics
- Waves are a way that energy is moved from one place to another.
- All waves have certain features: amplitude, wavelength, frequency and speed.
- The amplitude is the maximum disturbance caused by a wave, from the midpoint to the crest or trough.
- The wavelength is the distance for one complete wave.
- The frequency is the number of complete waves passing a point each second.
- The speed of the wave is how fast the energy is transferred (or the wave moves).
Types of Waves
- There are two types of waves: transverse and longitudinal.
- Transverse waves are waves where the vibrations are at right angles to the direction of travel. Light and other electromagnetic waves are transverse waves.
- Longitudinal waves are waves where the vibrations are in the same direction as the direction of travel. Sound waves are a type of longitudinal wave.
Properties of Waves
- Waves can be reflected, refracted and diffracted.
- Reflection occurs when waves bounce off a surface. The angle of incidence equals the angle of reflection.
- Refraction is the changing of direction of a wave as it passes from one medium to another.
- Diffraction is the spreading out of waves when they pass through a gap or around an object.
Electromagnetic Waves
- Electromagnetic waves are a type of transverse wave that includes a vast range of waves such as gamma rays, X-rays, ultraviolet light, visible light, infrared, microwaves, and radio waves.
- They all travel at the same speed in a vacuum, known as “the speed of light” (3 x 10^8 m/s).
- Their frequency determines their energy and type. High frequency waves (like gamma rays) have lots of energy while low frequency waves (like radio waves) have less energy.
Mechanical Waves
- Mechanical waves require a medium to travel through, such as air, water or a solid.
- Sound is an example of a mechanical wave. It is sent through the air (or another medium) as a series of compressions and expansions.
Wave Interference
- Waves can add together or cancel each other out. This process is called interference.
- Constructive interference occurs when waves add together to make a larger wave.
- Destructive interference occurs when two waves cancel each other out to make a flat line.