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**1. Homework Statement**

A permanent electric dipole consisting of charges +q and -q

separated by the fixed distance s. Charge +Q is distance r from

the center of the dipole. We'll assume s << r.

a) Use the binomial approximation (1+x)

x << 1 to show that the net force exerted on the dipole by charge +Q

is F

A permanent electric dipole consisting of charges +q and -q

separated by the fixed distance s. Charge +Q is distance r from

the center of the dipole. We'll assume s << r.

a) Use the binomial approximation (1+x)

^{-n}~= 1-nx ifx << 1 to show that the net force exerted on the dipole by charge +Q

is F

_{net}= 2KqQs/r^{3}## Homework Equations

F = Kqq/r

^{2}

**3. Attempted Solution**

F = +kQq/(r+s/2)

^{2}- kQq/(r-s/2)

^{2}

F = -2kQq(rs)/( (r+s/2)

^{2}* (r-s/2)

^{2})

i cannot figure out the rest from there...