GEOPH424 Final: GEOPHYS 424 UofA Final Exams 2014 424 Final Exam Winter
Document Summary
Wednesday april 23rd 2014, 9 am noon. Cell phones and all other electronic devices must be switched off and stored. All questions must be directed to the invigilator. Question 1 : maxwell"s equations (total = 28 points) A plane em wave is travelling vertically downwards in the earth in the z-direction. The wave has an angular frequency, , and time dependence ei t. The electric field is polarized in the x-direction. At this location, the earth has the following properties. = c (a) show that maxwell"s equations reduce to an ordinary differential equation for ex. Clearly explain all assumptions made in your derivation (b) indicate the type of electric current that is represented by each term on the right hand side of this equation. Simplify this equation by discarding the smaller term. (c) find a solution to the equation in (a) of the form ex = aekz where z increases positively (8 points) (6 points) into the earth.
