Class examples for Chapter 22

# Class examples for Chapter 22 - Class examples for Chapter...

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1 Class examples for Chapter 22 8. We place the origin of our coordinate system at point P and orient our y axis in the direction of the q 4 = –12 q charge (passing through the q 3 = +3 q charge). The x axis is perpendicular to the y axis, and thus passes through the identical q 1 = q 2 = +5 q charges. The individual magnitudes | |, | |, | |, E E E 1 2 3 and | | E 4 are figured from Eq. 22-3, where the absolute value signs for q 1 , q 2 , and q 3 are unnecessary since those charges are positive (assuming q > 0). We note that the contribution from q 1 cancels that of q 2 (that is, | | | | E E 1 2 ), and the net field (if there is any) should be along the y axis, with magnitude equal to E q d q d q d q d net j j F H G I K J F H G I K J 1 4 2 1 4 12 4 3 0 4 2 3 2 0 2 2 b g which is seen to be zero. 12. The field of each charge has magnitude   19 9 2 2 6 2 22 1.60 10 C (8.99 10 N m C ) 3.6 10 N C. (0.020 m) 0.020m kq e Ek r The directions are indicated in standard format below. We use the magnitude-angle notation (convenient if one is using a vector-capable calculator in polar mode) and write (starting with the proton on the left and moving around clockwise) the contributions to E net as follows: E E E E E            20 130 100 150 0 b g b g b g b g b g . This yields 393 10 764 6 . . c h , with the N/C unit understood. (a) The result above shows that the magnitude of the net electric field is 6 net | | 3.93 10 N/C. E  (b) Similarly, the direction of E net is –76.4 from the x axis. 22. (a) We use the usual notation for the linear charge density: = q/L . The arc length is L = r with is expressed in radians. Thus, L = (0.0400 m)(0.698 rad) = 0.0279 m.

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## This document was uploaded on 11/04/2011 for the course PHY 108 at SUNY Buffalo.

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Class examples for Chapter 22 - Class examples for Chapter...

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