Q144 / 160 · AP EAMCET 2024 (18 May Shift 1) · Physics

Two point charges $+6 \mu \mathrm{C}$ and $+10 \mu \mathrm{C}$ kept at certain distance repel each other with a force of 30 N . If each charge is given an additional charge of $-8 \mu \mathrm{C}$, the two charges

  • Correct answer
    A
    Attract with a force of 2 N
  • B
    repel with a force of 2 N
  • C
    Attract with a force of 15 N
  • D
    repel with a force of 15 N

Solution

$\mathrm{F}=\frac{\mathrm{kq}_1 \mathrm{q}_2}{\mathrm{r}^2} \Rightarrow 30=\frac{\mathrm{k}(6)(10)}{\mathrm{r}^2} \Rightarrow \frac{\mathrm{k}}{\mathrm{r}^2}=\frac{1}{2}$ Now, it $-8 \mu \mathrm{c}$ charge given on indivisual charge then, $\begin{aligned} & \mathrm{F}^{\prime}=\frac{\mathrm{k}(6-8)(10-8)}{\mathrm{r}^2}=\frac{1}{2} \times(-2) \times(2)=-2 \mathrm{~N} \\ & \therefore \quad \mathrm{~F}^{\prime}=2 \mathrm{~N}(\text { Attract })\end{aligned}$

Hence, the correct answer is option: 'A'.

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