3. please answer all parts fully (including bonus), thanks.

Use the following information to answer the next question. A student conducting a photoelectric effect experiment shines light of variable frequency onto the cathodes of three photocells, each with a different metal cathode. The resulting graph lines are shown below on the same grid. Maximum Kinetic Energy versus Frequency 8- Metal I Metal II 6- Metal III Ek max (eV) 12 16 20 24 28 f (10 * Hz) The graph shows how the maximum kinetic energy of photoelectrons depends upon the frequency of the incident radiation for three different metals. 1. a) Determine the slope of the graph line for metal II. (2 marks) (6.5, 0 ) 6 0- 35 b) What is the significance of the slope? 17. 1 (1 mark) ( 24 , 6 ) 0-43 c) Determine the threshold frequency for metal III. (2 marks) d) Which metal would be the best choice for a solar panel? Explain. (2 marks) Bonus: An x-ray light source with a wavelength of 1.77 x 10"I'm is shot at a piece of graphite. On the other side, the x-ray is observed to have scattered at an angle of 30.8 away from the original path. Determine the speed of the ejected electron