Structure of the Atom
De Broglie waves
$ 2d \sin \theta = n \lambda $
Light
$ E = h v ; v = c = v\lambda$
$ v = \frac {c}{\lambda}$
Planck : $ E = \frac {hc}{\lambda}$
Maxwell $ \bigcup_v = \pi c$
$\left[\therefore \bigcup = \text{Energy density}, \pi = \text{Mom density}\right]$
n $\rightarrow$ Number density of photons.
Photon Energy
Each photon carries an energy hv.
c = $v\pi$
$\therefore \bigcup_v= nhv = \pi_v c$
$\pi_= \frac {nhv}{c} = \frac {nh}{\pi}$
$\frac {h}{\pi}$ is the momentum carried by each photon.
Matter
Particle :
NR: E = $\frac {p^2}{2m} = \frac {1}{2} mv^2$
p = mv
ER = E = $ \frac {mc^2}{\sqrt{1-v^2/c^2}}$
p = $\frac {mv}{\sqrt{1-v^2/c^2}}$
Wave: $\quad \quad $ E = hv
p $= \frac {h}{v}$ ,$\qquad \qquad$ p $= \frac {h}{\lambda}$
$V_{wave} = v \lambda$ = $\frac {E}{H} \frac{h}{p} = \frac{E}{p}$
$V_{wave} = v\lambda = \frac {E}{p}$
$V^{WR}_{part} = \frac {p}{m}$
$V^{re}_{part} = \frac{pc^2}{\epsilon}$
There is a Discrepancy.
Particle Speed
$V=v\lambda$
$V_w = \frac{V_p}{2}$ for NR case.
$ = \frac{c^2}{v} $ for relativistic case.
Pilot waves
Early Speculations
India : Kanda (Vaisheshika School)
Greece: Democritus
England: Isaac Newton , Dalton…………
Other schools : The great elements (Greece, India)
Indirect Evidence
Models of Atoms
Two major Contenders
Source : ${ }^{214}_{83} Bi;$
Energy of $\alpha$ particle 5.5 MeV
Target: A very thing gold foil $(2.1 \times 10{-7})$
Detector : Zinc Sulphide (scintillation) + Microscope.
Rutherford Cross-Section
Modelling the Results
Important features
Basic assumption
Analysis of the Rutherford Experiment
$m_c = 0.5 Mev /c^2$
$m_{\alpha} = 4 GeV/c^2$
1MeV = $10^6$ eV
$\frac {m_e}{m_\alpha} = \frac {0.5 \times 10^6}{4 \times 10^9} \approx 10^{-4} $
8000 = $\frac{1}{8000}$
Atom
Atom Size
$R \leq 10{-10}m$
$\gamma_{min} = \frac {87 \times 2 \times e^2}{4 \pi \epsilon_0 \times 5.5 MeV}$
$ \approx 10{-14}m$
Thank you