A) 22.5cm
B) 18 cm
C) 36 cm
D) 30 cm
Correct Answer: D
Solution :
Let at point D intensity is zero \[\therefore \] \[\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{10\times {{10}^{-6}}}{{{x}^{2}}}=\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{40\times {{10}^{-6}}}{{{(90-x)}^{2}}}\] \[\frac{1}{{{x}^{2}}}=\frac{4}{{{(90-x)}^{2}}}\] \[\Rightarrow \] \[\frac{1}{x}=\frac{2}{90-x}\] \[90-x=2x\] \[\Rightarrow \] \[3x=90\] \[\therefore \] \[x=30\text{ }cm\]You need to login to perform this action.
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