A beam of unpolarised light of wavelength 400nm and power 5.0mW is incident normally on a linear polariser whose transmission axis is oriented at 45∘ to a reference axis. Immediately after the polariser a clean sodium surface (work function 2.2eV) is placed perpendicular to the beam. A photosensitive ammeter connected to the sodium surface measures the photocurrent produced.
(i) Calculate the number of photons striking the polariser per second.
(ii) Determine the number of photons per second incident on the sodium surface after passing through the polariser.
(iii) Find the maximum kinetic energy of the electrons emitted from the sodium surface.
(iv) If the emergent light beam (after the polariser) is sent, simultaneously, through a double–slit arrangement to form an interference pattern on a distant screen, comment on whether the polarisation introduced in the beam affects (1) the observed fringe width and (2) the measured photocurrent. Give reasons for your answers.
a. (i) –
b. (ii) –
c. (iii) –
d. (iv)(1) –
e. (iv)(2) –