Ultraviolet light of wavelength falls on a metallic surface and the measured stopping…

PHYSICS · Subjective · CBSE · Physics · Dual Nature of Radiation and Matter · Dual Nature of Radiation and Matter

Problem

Ultraviolet light of wavelength

330\,\text{nm}

falls on a metallic surface and the measured stopping potential is

0.7\,\text{V}

. When the wavelength of the incident radiation is reduced to

220\,\text{nm}

, the stopping potential rises to

2.5\,\text{V}

. (a) Using only these two experimental readings, obtain a numerical value for

h/e

. (b) Calculate the work function of the metal in electron-volt. (c) The work functions of three metals are: Potassium

2.3\,\text{eV}

, Calcium

3.2\,\text{eV}

, Aluminium

4.0\,\text{eV}

. Identify which of these metals the specimen is most likely to be and justify your choice.