Waves Flashcards
For a moving observer: When do you add or subtract Uo
Towards: Add
Away: Subtract
For a moving source: when do you add and subtract Us
Towards: Subtract
Away: Add
What is a travelling wave?
A wave that transfers energy but not matter
What is a transverse and longitudinal wave
Transverse: Particles oscillate perpendicular to direction of energy transfer
Longitudinal: particles oscillate parallel to direction of energy transfer
What is time period and frequency
Time Period: Time taken for 1 complete oscillation
Frequency: Number of oscillations that pass a point in 1s
For a Displacement-Distance Graph:
Which direction shows a positive and negative displacement
What can you find with the graph
- Positive = Right
Negative = Left - Wavelength and amplitude
For a Displacement-Time Graph:
What does the graph represent
What can you find using the graph
- Movement of 1 particle
- Amplitude, Time Period, Frequency
Phase Difference:
What is the definition
What multiples of pi means is in phase and completely out of phase
- Fraction of a wavelength that one lags
the other - In phase: 2π, 4π…
Completely out of phase: 1π, 3π…
What are rays and wavefronts
Wavefront: Shows parts of waves that are
in phase with each other
Rays: Are perpendicular to the wavefronts
and show direction of energy
transfer
What is refraction
Change of wavelength, speed and direction of a wave as it passes into a new medium
What is the equation for index of refraction
n1 = c / v1
c = speed of light in vacuum
v1 = speed of light in medium
What are the 6 things that happens when a wave meets a boundary
Transmission
Reflection
Refraction
Diffraction
Absorption
Scattering
What happens to speed, wavelength, change in angle and frequency as a wave enters a dense medium
Speed: Decreases
Wavelength: Decreases
Change in Angle: 0̷1 > 0̷2
Frequency: Same
What is the angle of refraction at the critical angle
90°
What is superposition
When 2 or more waves cross, the resultant displacement equals the vector sum of individual displacements