Progressive Waves Flashcards
1
Q
What is a progressive wave?
A
- A wave that transfers energy from one point to another without transferring the medium itself (without transferring any material)
2
Q
What is the difference between a Displacement-Distance and Displacement-Time graph?
A
- A displacement-distance graph is a snapshot of all the oscillating particles ‘frozen’ in time
- A displacement-time graph shows one particle and how its displacement changes with time
3
Q
What is the difference between wavelength and time period?
A
- Wavelength, λ, measured in metres, is the distance between points on successive oscillations of the wave that are in phase (In Displacement-Distance graphs)
- Time Period, T, measured in seconds, is time taken for one complete oscillation or cycle of the wave (In Displacement-Time graphs)
4
Q
What is the amplitude?
A
- Amplitude, A, measured in metres, is the maximum displacement of a particle in the wave from its equilibrium position
5
Q
What is the frequency?
A
- Frequency, f, measured in hertz, is the number of complete oscillations per unit time
6
Q
What is the equation for frequency?
A
- F = 1/T
7
Q
What is the equation for wavespeed?
A
- v = fλ
- Or c = fλ if it asks about electromagnetic waves traveling in a vacuum (where c is the speed of light at 3 x 10^8 m/s^-1)
8
Q
What does the wave speed equation show?
A
- As the wavelength increases, the frequency decreases
- As the wavelength decreases, the frequency increases
9
Q
What is the phase difference?
A
- The phase difference between two progressive waves is a measure of how much a point or a wave is in front or behind another
- Two points on a wave are in phase if they are both at the same point in the wave cycle (Has same velocity and displacement)
- When the crests or troughs are aligned, the waves are in phase
- When the crest of one wave aligns with the trough of another, they are in antiphase
- Phase difference is measured in fractions of a wavelength, degrees or radians
10
Q
How can you calculate phase difference?
A
- The phase difference can be calculated from two different points on the same wave or the same point on two different waves
- λ/2 = 180 degrees = π radians
- Two points with phase difference of 0 degrees or 360 degrees or a multiple of 360 degrees (Multiple or 1 full cycle of a wave) are in phase
- Points with phase difference of odd number multiples 180 degrees (π radians, or half a cycle) are exactly out of phase.