Please help me out. :)

An unknown charge and a charge of 60 nC are 2m apart. The electric field intensity is O at a point 0.8m from the unknown charge on the line connecting the two charges. Find the unknown charge.

Question

Please help me out. :)

An unknown charge and a charge of 60 nC are 2m apart. The electric field intensity is O at a point 0.8m from the unknown charge on the line connecting the two charges. Find the unknown charge.

anonymous · Answer

The electric field is defined as: $\vec{E} = \vec{F}/\left| q \right|$

anonymous · Answer

So, if the electric field is zero, then the force on that point is zero

anonymous · Answer

$\sum \vec{E} = \vec{0}$ 
$$\frac{k*q_1}{(2+0.8)^2} + \frac{k*q_2}{0.8^2} = 0$$, solve for $q_2$, where $q_1=60nC$

anonymous · Answer

and $k = 8.99\times10^9 N.m^2/C^2$

anonymous · Answer

I'll just give my final answer...
Unknown Charge = 2.667 x 10^-8 N/C
Is it right?