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Grade 12Electric Current

A charge +q is fixed at each of the points x = x. , x = 3x. , x = 5x. and so on to infinity on the x-axis and a charge -q is fixed at each of the points x = 2x. , x = 4x. , x = 6x. and so on to infinity. Here x. is a positive constant. Take the electric potential at a point due to a charge Q at a distance r from it to be Q/(4*pie*epsilon.*r). Then the potential at the origin to the above system is:-

Profile image of Samah Farooq
9 Years agoGrade 12
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2 Answers

Profile image of Sameer Baheti
ApprovedApproved Tutor Answer9 Years ago
Since potential is a scalar, the potential due to all charges separately can be written at the origin and added to get the answer. The potential due to all charges when added gives kq/x -kq/2x +kq/3x -kq/4x ...and so on to infinity. This can also be written as kq.ln2/x. As the expansion of ln(1+x) is x-x.x/2+x.x.x/3-x.x.x.x/4+ and so on for x belonging to [-1,+1]
Profile image of ankit singh
5 Years ago

Potential at origin due to positive charge

V(+)=x0Kq+3x0Kq+5x0Kq......
Similarly,
V()=[2x0Kq+4x0Kq+6x0Kq......]
Net potential 
Vnet=x0Kq2x0Kq+3x0Kq4x0Kq......
Vnet=x0Kq[121+3141......]
Vnet=x0Kqln2