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gen/lti/main.uni Return to Blackboard Halliday, Fundamentals of Physics, 10e Sys

ID: 3308636 • Letter: G

Question

gen/lti/main.uni Return to Blackboard Halliday, Fundamentals of Physics, 10e System Announcements (1 Unread) BACK NEXT PRINTER VERSION Flying Circus of Physics When a shower is turned on in a closed bathroom, the splashing of the water on the bare tub can fill the room's air with negatively charged ions and produce an electric field in the air as great as 1000 N/C. Consider a bathroom with dimensions 2.9 m x 2.6 m x 2.7 m. Along the ceiling, floor, and four walls, approximate the electric field in the air as being directed perpendicular to the surface and as having a uniform magnitude of 724 N/C. Also, treat those surfaces as forming a closed Gaussian surface around the room's air. What are (a) the ime charge density and (b) the number of excess elementary charges e per cubic meter in the room's air? (a) Number Units Units (b) Number SHOW HINT MATH HELP VIDEO MINI-LECTURE LINK TO TEXT LINK TO SAMPLE PROBLEM LINK TO SAMPLE PROBLEM 655 PM

Explanation / Answer

(A) from Gauss law,

net flux = Qin / e0

{ flux = E.A}

(724 x 2)((2.9 x 2.6) + (2.6 x 2.7) + (2.7 x 2.9)) = Q / (8.854 x 10^-12)

Q = 287 x 10^-9 C or 287 nC

volume charge density = (287 x 10^-9) / (2.9 x 2.6 x2.7)

= 14.1 x 10^-9 C / m^3

or 14.1 nC/m^3

(B) m = (14.1 x 10^-9) / (1.6 x 10^-19)

n = 8.81 x 10^10 no unit