From 42fee6292110e2303d7f42d077a888d5c0abdb65 Mon Sep 17 00:00:00 2001 From: Andrew Lorimer Date: Tue, 4 Sep 2018 16:50:05 +1000 Subject: [PATCH] refine light & matter cheatsheet --- physics/light-matter-ref.md | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/physics/light-matter-ref.md b/physics/light-matter-ref.md index 170d6a4..c048891 100644 --- a/physics/light-matter-ref.md +++ b/physics/light-matter-ref.md @@ -16,7 +16,9 @@ $$f={c \over \lambda}$$ $$E=hf={hc \over \lambda}$$ -$$h=6.63 \times 10^{-34}\operatorname{J s}=4.12 \times 10^{-15} \operatorname{eV s}$$ +$$h=6.63 \times 10^{-34}\operatorname{J s}=4.14 \times 10^{-15} \operatorname{eV s}$$ + +$$ 1 \operatorname{eV} = 1.6 \times 10^{-19} \operatorname{J}$$ ## Force of electrons @@ -28,6 +30,7 @@ $$F=evB$$ - if $V_{\operatorname{supply}} > 0$, e- are attracted to collector anode - if $V_{\operatorname{supply}} < 0$, e- are attracted to illuminated cathode, and $I\rightarrow 0$ - $v$ of e- depends on ionisation energy (shell) +- max current depends on intensity ### Threshold frequency - *threshold frequency* $f_0$ - minimum frequency for photoelectrons to be ejected @@ -45,13 +48,15 @@ $$\phi=hf_0$$ $$E_{\operatorname{k-max}}=hf - \phi$$ -voltage in circuit = max $E_K$ in eV +voltage in circuit or stopping voltage = max $E_K$ in eV +equal to $x$-intercept of volts vs current graph (in eV) ### Stopping potential _Smallest voltage to achieve minimum current_ -$$V_0 = {E_{K \operatorname{max}} \over q_e} = {{hf - \phi} \over q_e}$$ + +$$V=h_{\text{eV}}(f-f_0)$$ ## De Broglie's theory -- 2.47.1