Q 11 :

A $10\mu \text{C}$ charge is divided into two parts and placed at 1 cm distance so that the repulsive force between them is maximum. The charges of the two parts are       [2023]

• $9\mu \text{C},1\mu \text{C}$

   

• $5\mu \text{C},5\mu \text{C}$

   

• $7\mu \text{C},3\mu \text{C}$

   

• $8\mu \text{C},2\mu \text{C}$

   

Q 12 :

A point charge $q_1=4q_0$ is placed at the origin. Another point charge $q_2=-q_0$ is placed at $x=12$ cm. The charge of a proton is $q_0$. The proton is placed on the $x$-axis so that the electrostatic force on the proton is zero. In this situation, the position of the proton from the origin is ________ cm.              [2023]

Q 13 :

Three point charges $q$, $-2q$ and $2q$ are placed on the $x$-axis at distances $x=0$, $x=\frac{3}{4}R$ and $x=R$ respectively from the origin, as shown. If $q=2\times {10}^{-6}\text{\hspace{0.05em}C}$ and $R=\text{2\hspace{0.05em}cm}$, the magnitude of the net force experienced by the charge $-2q$ is _______ N.                    [2023]

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