$$E=hf={hc \over \lambda}$$
-$$h=6.63 \times 10^{-34}\operatorname{J s}=4.12 \times 10^{-15} \operatorname{eV s}$$
+$$h=6.63 \times 10^{-34}\operatorname{J s}=4.14 \times 10^{-15} \operatorname{eV s}$$
+
+$$ 1 \operatorname{eV} = 1.6 \times 10^{-19} \operatorname{J}$$
## Force of electrons
- 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
$$E_{\operatorname{k-max}}=hf - \phi$$
-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_
-$$V_0 = {E_{K \operatorname{max}} \over q_e} = {{hf - \phi} \over q_e}$$
+<!-- $$V_0 = {E_{K \operatorname{max}} \over q_e} = {{hf - \phi} \over q_e}$$ -->
+$$V=h_{\text{eV}}(f-f_0)$$
## De Broglie's theory