VISUAL PHYSICS ONLINE

7.1 THE NATURE OF LIGHT

ELECTROMAGNEITC WAVES

P71 007

A student carried out an experiment on the photoelectric effect. The frequency of the incident radiation and the energy of the photoelectrons were both determined from

measurements taken during the experiment.

(A) Graph the results.

(B) How could the reliability of the experiment be improved?

(C) The intensity of the incident radiation was tripled. How does it change the graph?

(D) Define the term critical frequency and estimate its value.

(E) Define the term work function and estimate its value.

View solution below only after you have completed the answering the question.

Solution

(A)

(B) Reliability – repeating an experiment several times - use mean value – graphing the results.

Ignore the data point that is obviously wrong

(C) No change to graph.

(D) Critical frequency – min frequency below which photo-current is zero.

f_c = 5´10¹⁴ Hz

(E) Work function – min energy to remove an electron from the surface.

W = 3.0´10^-19 J