in the formula, V= kq/r, what is k, q and r . Pls explain where and why is this formula usd and show the derivation too!!!!!! Pls!!!!!

V = potential at any point ...

V = kq/r 

another definition =>  workdone in bringing +ve test charge(q=1)  from infinity to a point which is at a distance r , near a charge q ...

F = k(q)(q_o)/r²                      (from culambs law)

q_o is +ve test charge , F is force bw test charge & q charge...

F = -dU/dr

dU/dr = -F = -kqq_o/r²

dU = -kqq_o(1/r²)dr             lim from infinity to r

U = -kqq_o(-1/r)                 lim infinity to r                     [   (1/r²)dr = -1/r     ]

U = kqq_o/r                  (q_o = 1)

so , U = kq/r

here K is columbs constant , k = 9*10⁹units , q is charge ...

this is the required result...

Approved

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