106use vector addition and the time will be 9:30
A clock face has charges -q,-2q,-3q,......-12q fixed at corresponding numerals on the dial .The clock hand do not disturb the net electric field due to point charges. At what time does the hour hand point the direction of net electric field at the centre of the dial.
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UP 0 DOWN 0 0 6
6 Answers
62chintan... think more in terms of symmetry...
You are on the right track...
1sir it should be near 12 according to me
more than 9 30
(i want to ask something that for a set of charges if the difference of 2 charges is same then its e field are same which takes place in clock 12-6,11-5...,7-1 then the resultant e field of all this will be same) if yes then its done 9 30 by symetry
62no that is not the reason chintan...
The reason is that those electric fields at the center will be exactly opposite in direction and hence cancel each other..
So we will be left with charges -6 at the points 7, 8, 9, 10, 11, 12