Electrostatics Question 505
Question: Two point charges +8q and $ -2q $ are located at $ x=0 $ and $ x=L $ respectively. The location of a point on the x-axis at which the net electric field due to these two point charges is zero is [AIEEE 2005]
Options:
A) 8 L
B) 4 L
C) 2 L
D) $ \frac{L}{4} $
Show Answer
Answer:
Correct Answer: C
Solution:
The net field will be zero at a point outside the charges and near the charge which is smaller in magnitude. Suppose E.F. is zero at P as shown. Hence at P; $ k.\frac{8q}{{{(L+l)}^{2}}}=\frac{k.(2q)}{l^{2}} $
therefore l = L. So distance of P from origin is L + L = 2L.
