Unit 11 -Waves 1 Flashcards
What is a progressive wave?
A means of transferring energy from one place to another without a transfer of matter between the two points.
What is the characteristics of a transverse wave?
The direction of oscillation of a wave is perpendicular to the direction of motion of the wave.
What is the characteristics of a longitudinal wave?
The direction of oscillation of a wave is parallel to the direction of motion of the wave.
What are examples of transverse waves?
All EM waves are transverse (e.g. radio waves,microwaves etc.)
What are examples of longitudinal waves?
Sound waves and p-waves
What is the definition of displacement?
Distance from the equilibrium position in a particular direction.
What does amplitude mean?
Maximum displacement from the equilibrium position
What is meant by wavelength?
Minimum distance between two points in phase on adjacent waves.
What is a period?
Time taken for one oscillation to pass a given point.
What is frequency?
Number of wavelengths passing a given point per unit time.
What is waves speed?
Distance travelled by the wave per unit time
What is phase difference?
It describes the difference between the displacements of the particles along a wave, or the difference between the displacements of the particles on different waves.
What does reflection mean?
When a wave changes direction at a boundary between two different media, remaining in the original medium.
When does refraction occur?
when a wave changes direction as it changes speed when it passes from one medium to another
What happens when a ray enters a dense medium?
Speed decreases
refraction ray goes towards the normal
What happens when a ray enters a less dense medium?
Speed increases
refraction ray goes away from the normal
What is diffraction?
The spreading out of a wave as it passes through an gap/aperture or when they encounter an obstacle
What is polarisation?
The particles oscillate along one direction only, which means that the wave is confined to a single plane.
What does intensity mean?
The radiant power passing through a surface per unit area measured in Wm-2.
Why do X-rays and gamma rays overlap?
Waves not classified by wavelength but by origin, X-rays are emitted by fast-moving electrons, whereas gamma rays come from unstable atomic nuclei
What is the critical angle?
The angle of incidence at the boundary between two media that will produce and angle of refraction of 90°
What is superposition?
When two waves of the same type cross at the same point in time and space. It is defined as “the vector sum of the two displacements”
