With reference to photoelectric effect, define threshold wavelength.

Define the following with reference to photoelectric effect$:$

$\left(\mathrm{a}\right)$ Threshold frequency $\left(f_o\right)$

Define the following with reference to photoelectric effect$:$

$\left(\mathrm{b}\right)$ Stopping potential $\left(V_s\right)$

In photoelectric effect experiment, the slope of the graph of the stopping potential versus frequency gives the value of:

State de Broglie hypothesis.

What conclusion can be drawn from Davisson and Germer's experiment?