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Unformatted text preview: Exam I Solutions Part A. Multiple choice questions. Check the best answer. Each question carries a value of 4 points. 1. All of the following statements about lines of the electrostatic Feld are true, but which one follows from the Feld equation E d A = 4 kQ enc ? ield lines do not cross each other. ield lines start on positive charges and end on negative charges. ield lines do not form closed curves. ield lines do not penetrate a conductor. 2. Concerning the relationship between E and V , which of these is wrong? If V is constant at all points of a solid object, then E = within the object. If E is not zero at a point, then V cannot be zero at that point. As one moves away from a positive charge both V and the magnitude of E decrease. If V depends only on the coordinate variables x and y then E z = . Physics 54 Summer 2010 1 3. In Case 1 shown below we have a thin hollow non-conducting spherical shell of radius R centered at the origin, with total charge Q spread uniformly over its surface; inside the shell, at distance d from the origin, is a point charge + Q . In Case 2 we have a dipole, with charges Q separated by distance d , and with the negative charge located at the origin. The E-Feld in the two cases is the same: Everywhere. Nowhere. Only at points at distance greater than R from the origin. [In that region the Feld of the shell in Case 1 is the same as that of the negative charge at the origin in Case 2.] Only at points at distance less than R from the origin. d + Q Q Q + Q d Case 1 Case 2 4. When two identical capacitors are connected in parallel across a battery the total charge on the combination is Q . If they are discharged and then connected in series across that battery the charge on each is: Q /2....
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- Summer '09