5 - Waves and Particle Nature of Light Flashcards
Define oscillation
Motion that repeats at regular intervals (periodic oscillation/harmonic motion)
One wave cycle = ?
One oscillation (2π/360°)
Define wave phases
They describe the stage of a wave’s oscillation
What is the phase difference when waves are in antiphase?
π (180°)
What is the phase difference when waves are said to be ‘in phase’?
They are at the same stage, so 0
What is the phase difference when waves are said to be in quadrature?
π/2 (90°)
f = ?
1/T
Transverse waves have oscillations ___ to its propagation?
Perpendicular
Longitudinal waves have oscillations ___ to its propagation?
Parallel
What does the microphone in the oscilloscope traces core practical do?
Uses small movements of its diaphragm to produce an electrical signal that mimics variation of pressure/displacement in a wave
What happens to amplitude when two waves (with same amplitude) are in phase?
Amplitude doubles (constructive intereference)
What happens to amplitude when two waves (with same amplitude) are in antiphase?
No amplitude (destructive interference)
Conditions for 2 waves to be coherent when in phase
-All peaks/troughs line up
-Waves have same amplitude and wavelength
-Constant frequency
Conditions for 2 waves to be coherent when they are out of phase
-Consistent phase difference
-Same amplitude and wavelength
-Constant frequency
Define standing wave
Due to the superposition of 2 waves with the same amplitude and frequency traveling at the same speed but in opposite directions
What is the phase change of a standing wave at the fixed end?
π (180°)
Define node
Points of 0 displacement on a standing wave
Define antinode
Points of maximum displacement on a standing wave
Distance between 2 nodes
λ/2
Distance between a node and antinode
λ/4
How does mass and tension affect frequency on a plucked string?
-Tension increase = frequency increase
-Length decrease = frequency increase
-Mass per unit length decrease = frequency increase (thinner string)
Define diffraction
The spreading out of waves when they pass through a gap/around an obstacle, especially when the size of the gap/obstacle is comparable to the wavelength of the waves
Define superposition
The principle that when 2 or more waves overlap, the resultant displacement at any point is the sum of the displacements of individual waves at that point
Define interference
The phenomenon that occurs when 2 or more waves meet and combine, resulting in a new wave pattern