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I have a question about these electric field strength formulas

Why is \$E_1=\frac{F}{q}=\frac{K\frac{Q_1 Q_2}{x^2}}{Q_2}\$, instead of \$=\frac{K\frac{Q_1 Q_2}{x^2}}{Q_1}\$?

\$K\$ is constant \$=9 \times 10^9\$

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  • \$\begingroup\$ Where did the formulas come from specifically? \$\endgroup\$ – Andy aka Apr 10 at 12:16
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    \$\begingroup\$ Please do something about the title text, it's a mess. \$\endgroup\$ – Wossname Apr 10 at 12:37
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The first formula - the one which you do not agree with - can not be correct, since it has a wrong dimension -- assumed that K has the usual Am/Vs or m/F units. Also K can not be dimensionless.

I am also not 100% sure what is denoted by E_1. If it is the electric field at P due only to Q_1, than $$ E_1 = \frac 1 {4 \pi \epsilon_0} \frac {Q_1 Q_2} {x^2}$$. If you should consider the effect of Q_2, just use superposition.

PS: please avoid formulas in the title. It is hard to read and take some time to be rendered in the browser.

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As there is no negative sign with 'Q1' or 'Q2', so both of them are positive. So, if a unit positive charge is placed at point 'P', then 'E1' would indicate the direction of repulsive force due to 'Q2'. Which means, 'E1' is the electric field intensity due to 'Q2'.

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