For a particular metal

PHYSICS · Multi-part · A Level · Physics · Particles and radiation · Particles and radiation

Problem

For a particular metal, the work function is

3.0\,\text{eV}

. Three monochromatic light sources are available:

A

with wavelength

300\,\text{nm}

B

with wavelength

420\,\text{nm}

and

C

with wavelength

650\,\text{nm}

. Use

h=6.63\times10^{-34}\,\text{J\,s}

c=3\times10^{8}\,\text{m\,s}^{-1}

and

e=1.6\times10^{-19}\,\text{C}

. (i) Identify which of the three sources will produce photoelectric emission from the metal. Support your answer with suitable calculations. (ii) For each source that is capable of producing emission, calculate the stopping potential

V_0

required to reduce the photocurrent to zero. (iii) Using the values obtained in part (ii), sketch qualitatively (no numerical scale required) a graph of stopping potential

V_0

versus photon frequency

\nu

. Mark clearly the intercept on the frequency axis.

Related theory

Electron Emission
Einstein's Photoelectric Equation
Quantum Explanation of PE
Photoelectric effect
Dual Nature of Radiation and Matter
The photoelectric effect

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