# Physics - Waves

> Source: https://ollybritton.com/notes/a-level/physics/topics/waves/ · Updated: 2024-08-25 · Tags: physics, waves, school, year-1

## Flashcards
##### What is the symbol for wavelength??
$$
\lambda
$$

##### What is the symbol for the period of oscillation in a wave??
$$
T
$$

##### What is the symbol for wave speed??
$$
v
$$

##### What is the frequnecy of a wave??
The number of wavelengths passing through a given point per unit time.

##### What is the period of oscillation of a wave??
The time taken for a wave to move one whole wavelength past a given point.

##### What is the wavelength??
The distance between any point on a wave and then next identical point on an adjacent wave.

##### What is the wave speed??
The distance travelled by the wave per unit time.

##### What is the wave equation, in terms of $v$, $f$ and $\lambda$??
$$
v = f\lambda
$$

##### What is the formula for frequency in terms of period $T$??
$$
f = \frac{1}{T}
$$

##### What is a progressive wave??
A wave that transfers energy but not matter.

##### What is a transverse wave??
A wave where the oscillations are perpindicular to the direction of energy transfer.

##### What is a longitudinal wave??
A wave where the oscillations are parallel to the direction of energy transfer.

##### What is a mechanical wave??
A wave that requires a medium to travel through.

##### What is a wave that requires a medium to travel through called??
A mechanical wave.

##### What is special about electromagnetic waves??
They don't require a medium to travel through.

##### What is the name for waves that don't require a medium to travel through??
An electromagnetic wave.

##### In a longitudinal wave, what's one way you could measure the wave length??
Find the distance between a pair of compressions/rarefactions.

##### What is the main difference between transverse and longitudinal waves??
In a transverse wave, oscillations are perpindicular to energy transfer whereas they are parallel in a longitudinal wave.

##### Since transverse and longitudinal waves are both progressive waves, what must be true??
They both transfer enrgy but not matter.

##### ![PHOTO WAVE RAREFACTION](wave-rarefaction.png) What is this called??
A rarefaction.

##### ![PHOTO WAVE COMPRESSION](wave-compression.png) What is this called??
A compression.

##### ![PHOTO WAVE NO EQUILIBRIUM](paste-dea9b07d326e05781aa2e2a309aa5b24ceae43b2.jpg) What is missing??
The equilbrium position.

##### ![PHOTO WAVE NO PEAK](wave-no-peak.png) What is missing??
The peak.

##### ![PHOTO WAVE NO TROUGH](wave-no-trough.png) What is missing??
The trough.

##### ![PHOTO WAVE NO AMPLITUDE](wave-no-amplitude.png) What is missing??
Amplitude.

##### ![PHOTO WAVE NO WAVELENGTH](wave-no-wavelength.png) What is missing??
Wavelength.

##### What is a wave profile??
A displacement-distance graph.

##### On a displacement-distance graph, what is on the $x$ axis??
Distance.

##### On a displacement-distance graph, what does the distance between two troughs equal??
The wavelength.

##### On a displacement-time graph, what does the time between two troughs equal??
The period.

### 2021-02-09
##### ![PHOTO PHASE VISUAL](phase-visual.gif) What does this demonstrate??
The phase of a point on the wave.

##### What is phsae difference measured in??
* Degrees
* Radians

##### ![PHOTO PHASE VISUAL](phase-visual.gif) How does the angle the radius makes with the circle relate to the wave??
That's the phase of the point on the wave.

##### ![PHOTO PHASE POINTS](phase-points.png) What is the phase difference between $A$ and $E$??
$$
360^{\circ}
$$

##### ![PHOTO PHASE POINTS](phase-points.png) What is the phase difference between $A$ and $C$??
$$
180^{\circ}
$$

##### ![PHOTO PHASE POINTS](phase-points.png) What is the phase difference between $B$ and $D$??
$$
180^{\circ}
$$

##### ![PHOTO PHASE POINTS](phase-points.png) What is the phase difference between $B$ and $C$??
$$
90^{\circ}
$$

##### What does it mean for two particles to be "in phase"??
They are oscillating perfectly in step with each other.

##### What does it mean for two particles being "in antiphase"??
They are oscillating perfectly out of step with each other.

##### ![PHOTO DISPLACEMENT DISTANCE 0](paste-3f9677aaad41dffa5113410b5f43c226ba12dca9.jpg) What would the wave profile for $T - \frac{T}{2}$ look like??
![PHOTO DISPLACEMENT DISTANCE HALF T](displacement-distance-half-t.png)

##### What's the formula for $\phi$, the phase difference in degrees between two points on a wave of wavelength $\lambda$ and seperated by a distance $x$??
$$
\theta = \frac{x}{\lambda} \times 360^{\circ}
$$

### 2021-06-08
##### What colour of visible light has the SHORTEST wavelength??
Blue.

##### What colour of visible light has the LONGEST wavelength??
Red.

### 2021-07-08
##### What is the principle of superposition of waves??
Displacement of a wave is equal to the sum of the displacements of the individual waves.

### 2021-09-19
##### What is the formula for the phase difference between two points with time difference $t$ and time period $T$??
$$
2\pi\left(\frac{t}{T}\right)
$$

##### What is the formula for the phase difference between two points with distance between $d$ and wavelength $\lambda$??
$$
2\pi\left(\frac{d}{\lambda}\right)
$$

### 2022-06-01
##### What is true about the amplitude of a wave $A$ and the distance from its source $r$??
$$
A \propto \frac{1}{r}
$$

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