An investigator studies an unfamiliar photoactive metal by measuring the stopping…

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

Problem

An investigator studies an unfamiliar photoactive metal by measuring the stopping potential

V_s

for three ultraviolet wavelengths. The results are listed below. Numerical data table:

Wavelength $\lambda$ (nm)	Stopping potential $V_s$ (V)
480	0.54
300	2.17
220	3.66

Take

c = 3.00\times10^{8}\,\text{m}\,\text{s}^{-1}

and

e = 1.60\times10^{-19}\,\text{C}

. (a) Convert each wavelength to its corresponding frequency and record your results in a new column added to the table. (b) Using any two of the data points, determine an experimental value for Planck’s constant

h

. Show all steps clearly. (c) From your value of

h

and the data, calculate the work function of the metal in electron-volts. (d) Predict the maximum speed of electrons ejected when the metal is illuminated with light of wavelength

180\,\text{nm}

. Assume non-relativistic motion and express your answer in

\text{m}\,\text{s}^{-1}

Related theory

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