Question

Two charges $-5\mu C$ and $+10\mu C$ are placed 20 cm apart. The net electric field at the mid-point between the two charge is

• A. $4.5\times {10}^{5}N/C$ directed towards $+10\mu C$
• B. $13.5\times {10}^{5}N/C$ directed towards $-5\mu C$
• C. $13.5\times {10}^{5}N/C$ directed towards $+10\mu C$
• D. $4.5\times {10}^{5}N/C$ directed towards $-5\mu C$

Answer 1

The correct option is B $13.5\times {10}^{5}N/C$ directed towards $-5\mu C$

R.E.F image

$\overline{E}net=\overline{E_1}+\overline{E_2}$

$=\frac{K(5\times {10}^{-6})}{10\times {10}^{-2}}+\frac{K(10\times {10}^{-6})}{10\times {10}^{-2}}$

$\Rightarrow 9\times {10}^9[5\times {10}^{-5}+10\times {10}^{-5}]$

$\Rightarrow 135\times {10}^4$ N\C

$\overline{E}net$ $13.5\times$ ${10}^5$ N/C towards $-5\mu c$