Physics

Problem

A clean sodium surface is irradiated by monochromatic light of frequency

6.5\times10^{14}\,\text{Hz}

(greater than the threshold frequency for sodium). The intensity of the incident light is then suddenly doubled while all other experimental conditions are kept unchanged. (i) On a single set of axes sketch qualitatively the photocurrent–applied potential (

I

–

V

) curves for the two different light intensities, clearly marking the saturation currents and stopping potentials. (ii) Explain with proper reasoning why one of the two plotted quantities changes whereas the other remains unaffected when the intensity is doubled. a. (i) Sketch the two

I

–

V

curves on the same axes, labelling

I_{\text{sat,1}}

I_{\text{sat,2}}

, and the common stopping potential

V_0

. b. (ii) State and justify which parameter (

I_{\text{sat}}

V_0

) is altered by the change in intensity and why the other parameter remains unchanged.

Browse the problem library