PHYSICS 3B Study Guide - Midterm Guide: Electric Flux, Electric Field, Energy Density
23 Nov 2015
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Electric forces and fields (8 points: a cube has edges 3. 00 cm in length. On one face of the cube, the electric field has a uniform magnitude of 5. 25 v/m and is directed outward, perpendicular to the face of the cube. On the opposite face, the electric field has a uniform magnitude of 7. 50 v/m and is directed inward, perpendicular to the face of the cube. The electric field is parallel to the other four faces of the cube. Find the charge inside the cube. (4 points) Use gauss"s law to find the charge inside the cube based on the electric flux through the surface. E = (0. 03 m)2 (+5. 25 v/m) + (0. 03 m)2 (-7. 50 v/m) = -2. 025 10-3 v m = qin/ 0. Qin = 0 e = (8. 854 10-12 c2/n m2) (-2. 025 10-3 v m) = -1. 79 10-14 c: four 1. 50 nc charges are placed at the corners of a square whose sides are 1. 25 mm.
