Physics 21Fall, 2005Solution to HW-221Q16Draw the electric feld lines surrounding two neg-ative electric charges a distancelapart.The feld lines are as in Fig. 21-33(b) on page 562, ex-cept the arrows ±or the feld direction point in the oppositedirection becausebothsigns have changed.21Q27Explain why there can be a net ±orce on an electricdipole placed in a nonuni±orm electric feld.A dipole consists o± a positive charge +qand a negativecharge−qa distancedaway. A uni±orm electric feld is thesame everywhere, so the feldE+at +qand the feldE-at−qare the same. The vector sum o± the ±orces on the dipoleis there±ore zero. For a nonuni±orm electric feld,E+can bedi²erent ±romE-, so the vector sum may not be zero.21P12A charge o± 9.00 mC is placed at each corner o±a square 0.200 m on a side. Determine the magnitude anddirection o± the ±orce on each charge.1234LQQQQxyF12F13F14The ±orce on charge 1 due to each o± the other charges isF1=F12+F13+F14.
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This note was uploaded on 08/06/2008 for the course PHYS 21 taught by Professor Hickman during the Fall '07 term at Lehigh University .