An experimenter measures the wavelength shift for photons that scatter from free…
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Modern Physics · Modern Physics
Problem
An experimenter measures the wavelength shift Δλ for photons that scatter from free electrons at several angles θ. The results are summarized in the table below.
Angle θ (deg) | Measured Δλ (pm)
30 | 0.33
60 | 1.20
90 | 2.45
120 | 3.62
150 | 4.50
180 | 4.87
Use the data to investigate whether the photon model is supported by the experiment.
(a) Show analytically that, according to the photon model, a plot of Δλ versus (1−cosθ) should be a straight line that passes through the origin.
(b) Using any two convenient data points from the table, determine an experimental value for the slope of that line. Hence calculate an experimental estimate of the constant mech in picometres.
(c) The accepted value of mech is 2.43pm. Compare this value with your result from part (b) and discuss the degree to which the data support the photon description over the classical wave description.