(5 points) The photoelectric effect is measured for Cs and Zn, by obtaining the retarding voltages that are needed to prevent the photoelectrons from reaching a collecting detector. The data for different wavelengths is given in the table below. a (nm) Retarding potential (V) Zn Cs 600 300 200 150 120 0.167 2.235 4.302 6.369 8.436 Not measured 0.435 2.502 4.567 6.636 (a) Plot the incident light frequency versus electron kinetic energy for these two metals. (b) Evaluate the work functions for Cs and Zn. (c) Obtain a value for Plancks constant h in J-sec for both sets of data. (d) Why is the work function for Cs so different than Zn? Think about the periodic table. Cs is often used as a photocathode material in photomultiplier tubes. Explain why. (e) What is the velocity of the outgoing electron for 150 nm photons with Zn in cm/sec