Wave

9.1

reflection:

phase: offset of the wave from a reference point

Name	Symbol	Unit
wavelength	$\lambda$	m
frequency	$f$	hz
period	$T$	s
wave speed	$v$	m/s

Equation	Explain
$v=f\lambda$
$f=\frac{1}{T}$

9.2

refraction: a: normal, b: at critical angle, c: total internal reflection

Name	Symbol	Unit
index of refraction	$n$	none
speed of light	$c$	m/s
critical angle	$\theta_{c}$	$^{\circ}$

Equation	Explain
$n=\frac{c}{v}$	$v$: speed of light in that material
$n_{1}sin\theta_{1}=n_{2}sin\theta_{2}$
$\frac{n_{2}}{n_{1}}=\frac{\lambda_{1}}{\lambda_{2}}$
$sin\theta_{c}=\frac{n_{2}}{n_{1}}$	$n_{1}$: from material $n_{2}$: to material

9.3

diffraction:

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interference:

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if $\lambda \geq w$: noticeable diffraction, else: very little

Name	Symbol	Unit
distance between two slits	$d$	m
node (destructive) number	$n$	-
antinode (constructive) number	$m$	-
distance from the center of the slit to the point / distance from the slit to the screen	$L$	m
distance from the center of the screen to the point	$x$	m
path length difference (difference of the distance from a point to two sources)	$\Delta s_{n}$	m

Equation	Explain
$dsin\theta_{n}=(n-\frac{1}{2})\lambda$	$\theta_{n}$: angle for the nth nodal line
$d\frac{x_{n}}{L}=(n-\frac{1}{2})\lambda$
$\Delta s_{n}=	PS_{1}-PS_{2}
$\Delta s_{n}=(n-\frac{1}{2})\lambd$

9.5 Double Slit

Name	Symbol	Unit
distance between light / dark spots on the screen	$\Delta x$	m

Equation	Explain
$dsin\theta=m\lambda$
$dsin\theta=(n-\frac{1}{2})\lambda$
$x_{m}=m\frac{L\lambda}{d}$
$x_{n}=(n-\frac{1}{2})\frac{L\lambda}{d}$
$\Delta x=\frac{L\lambda}{d}$

10.1 Thin Film

Light travelling in low $n$, reflected by high $n$ -> phase change by 180$^{\circ}$
Light travelling in high $n$, reflected by low $n$ -> phase doesn't change

Air Wedge:

Name	Symbol	Unit
Height of the thin film/air wedge	$t$	m
The number of extra wavelengths the wave travels in the film	$N$	-

Equation	Explain
$\lambda_{film}f_{film}=\frac{c}{n_{film}}$
$\lambda_{film}=\frac{\lambda_{vac}}{n_{film}}$
$N=\frac{2t}{\lambda_{film}}$
$x_{1}=\frac{L\lambda}{2t}$	Equation for an air wedge $x_{1}$: first destructive interference, also the seperation between the fringes

10.2 Single Slit

Name	Symbol	Unit
width of the slit	$w$	m
distance from the center of the screen to the point	$y$	m

Equation	Explain
$\Delta L=\frac{w}{2}sin{\theta_{n}}$
$wsin\theta_{n}=n\lambda$
$wsin\theta_{m}=(m+\frac{1}{2})\lambda$
$\Delta y=\frac{L\lambda}{w}$
$\Delta y=\frac{y_{n}}{n}$

10.4

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Last update: May 27, 2021
Created: May 5, 2021