Question

1. Plot a labelled graph of stopping potential (V_s) versus frequency (f) of incident UV radiation.
2. State how the value of Planck’s constant can be determined from this graph.

Answer 1

i.

ii. Applying Einstein’s photoelectric equation, [eV_s = hf − Φ], the equation of the line AB can be written as,

Vs = `(h/e)f - (Phi/e)`

The slope of the line = `h/e`

y-axis intercept of line = `-Phi/e`

Plank’s constant (h) = slope × e (In graph)