GEOPH424 Midterm: GEOPHYS 424 UofA midterm Exams 424Midterm Fall2014
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Note the number of points allocated for each part. Notes and textbooks may not be used during the exam. Please hand in this exam, with your name and student number listed above. Question 1 resistivity of rocks ( total = 9 points) The pore space of an isotropic sandstone is 80% saturated with salt water. The salt water has a salinity of 20 g per litre. The rock has isolated pores and a bulk resistivity of 50 m. Question 2 : maxwell"s equations (total = 14 points) A plane em wave with frequency, f, is travelling vertically downwards in the earth in the z-direction. The wave has an angular frequency, , and varies with time (t) as e-i t. The electric field is polarized in the x-direction. It can be shown that maxwell"s equations reduce to a single differential equation for ex. 0 x (2a) find a solution to this equation of the form ex = aekz.
