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## Homework Statement

A charge of -11.8 micro-Coulombs is placed on x axis at x=0 meters. Another charge of -7.3 micro-Coulombs is placed on x axis at x=+.42 meters. Other than infinity, where on x axis is total electric field equal to zero? Answer in centimeters.

q

_{1}=-11.8[tex]\mu[/tex]C

q

_{2}=-7.3[tex]\mu[/tex]C

## Homework Equations

E=kq/r

^{2}[tex]\widehat{}r[/tex]

## The Attempt at a Solution

E

_{1}=E

_{1}[tex]\widehat{}x[/tex]=-(8.99*10

^{9}9Nm

^{2}/C

^{2})(11.8*10

^{-6}C)/r

_{1}

^{2}[tex]\widehat{}x[/tex]

E

_{2}=E

_{2}[tex]\widehat{}x[/tex]=(8.99*10

^{9}Nm

^{2}/C

^{2})(7.3*10

^{-6}C)/r

_{2}

^{2}

E

_{x}=E

_{1x}+E

_{2x}=-(8.99*10

^{9}Nm

^{2}/C

^{2})(11.8*10

^{-6}C)/r

_{1}

^{2}+(8.99*10

^{9}Nm

^{2}/C

^{2})(7.3*10

^{-6}C)/r

_{2}

^{2}=0

11.8/7.3=r

_{1}

^{2}/r

_{2}^2

r

_{1}/r

_{2}=[tex]\sqrt{}11.8/7.3[/tex]