Chapter 4 - Waves Flashcards
What are the two types of waves?
Longitudinal waves and transverse waves.
What are electromagnetic waves?
Waves with oscillating electric and magnetic fields.
What are longitudinal waves?
Waves which oscillate parallel to the direction of energy transfer.
When is a transverse wave polarised?
When oscillations stay in one plane only.
What are transervse waves?
Waves which oscillate perpendicular to the direction of energy transfer.
What do polarising filters affect?
Light intensity.
What is the displacement of a vibrating particle?
The displacement from equilibrium position.
What is the amplitude of a wave?
The maximum displacement of a vibrating particle. Distance between equilibrium position and peak or trough.
What is the wavelength?
The distance between the same point on two adjacent waves. It is the complete cycle of a wave.
What is the period of a wave?
The time for one complete wave to pass a fixed point.
What is the frequency of a wave?
The number of complete waves passing a point per second, measured in Hz.
Equation for frequency.
f = 1/T, where T is the period.
What is the phase of a vibrating particle?
The fraction of the cycle the particle has completed since the start of the cycle.
Wave speed equation.
Wave speed, c = frequency X wavelength
What is the phase difference?
The fraction of a cycle between the vibrations of two particles, measured in degrees or radians. The two particles must be vibrating at the same frequency.
Phase difference equation.
Phase difference in radians = (2πd)/λ
Where d is the distance between particles and λ is the wavelength.
What are wavefronts?
The waves observed in a ripple tank which are lines of constant phase. Waves travel at right angles to the wavefront.
What is refraction?
When waves pass a boundary, causing them to change direction and speed.
What is diffraction?
When waves spread out after passing through a gap.
What is the principle of superposition?
The principle of superposition states that when two waves meet, the total displacement at a point is equal to the sum of the individual displacements at that point.
What are stationary waves?
Wave patterns with nodes and antinodes formed when two or more progressive waves of the same frequency and amplitude pass through each other.
What are progressive waves?
Waves which travel through a substance or through space if electromagnetic.
What is interference?
When waves are passing through each other with constant frequency and at a constant phase difference, causing cancellation and reinforcement at fixed positions.
What are coherent sources of waves?
Sources which vibrate at the same frequency and with constant phase difference.
What is a node?
A point on a harmonic of no displacement.
What is an antinode?
A point midway between nodes of a harmonic where amplitude is maximum.
Distance between adjacent nodes = Wavelength/2
Distance between adjacent nodes = Wavelength/2
Stationary waves that vibrate freely do not transfer energy to their surroundings.
Stationary waves that vibrate freely do not transfer energy to their surroundings.
Fundamental frequency, f1 = c/2L
Frequency of nth harmonic = nf1
Fundamental frequency = c/2L
Frequency of nth harmonic = nf1
