The drum of the photocpying machine in problem 16 has a length of 42cm and a diameter of 12cm. What is the total charge on the drum? In problem 16 it says, The e filed just above the surface of the charged drum of a photocopying machine has a magnitude E of 2.3x10^5 N/C. So I first found the charge density [itex]\delta[/itex]. E = [itex]\delta[/itex]/2PIEor; [itex]\delta[/itex] = E(2PI)(8.85x10^-12)(.006m) = 7.67x10^-8; Then i used [itex]\delta[/itex] = q/Surface Area. q = (2PIrh)[itex]\delta[/itex]; q = 2PI(.006m)(.042m)*7.67x10^-8 =(adsbygoogle = window.adsbygoogle || []).push({}); 1.21x10^-10Which is wrong. The book got .32x10^-6C. Any idea where i messsed up at?

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# Homework Help: Finding the charge of a drum, i got the steps i think

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