Electrostatics Question 492
Question: Point charge $ q _{1}=2\mu C $ and $ q _{2}=-1\mu C $ are kept at points $ x=0 $ and $ x=6 $ respectively. Electrical potential will be zero at points [MP PMT 2004]
Options:
A) $ x=2 $ and $ x=9 $
B) $ x=1 $ and $ x=5 $
C) $ x=4 $ and $ x=12 $
D) $ x=-2 $ and $ x=2 $
Show Answer
Answer:
Correct Answer: C
Solution:
Potential will be zero at two points At internal point (M) :$ \frac{1}{4\pi {\varepsilon _{0}}}\times [ \frac{2\times {{10}^{-6}}}{(6-l)}+\frac{(-1\times {{10}^{-6}})}{l} ]=0 $
therefore l = 2 So distance of M from origin; x = 6 ? 2 = 4 At exterior point (N) :$ \frac{1}{4\pi {\varepsilon _{0}}}\times [ \frac{2\times {{10}^{-6}}}{(6-l’)}+\frac{(-1\times {{10}^{-6}})}{{{l}^{’}}} ]=0 $
therefore $ l’=6 $ So distance of N from origin, x = 6 + 6 = 12
