Question
Question: Two equal point charges are fixed at x = –a and x = + a on the x-axis. Another point charge Q is pla...
Two equal point charges are fixed at x = –a and x = + a on the x-axis. Another point charge Q is placed at the origin. The change in the electrical potential energy of Q, when it is displaced by a small distance x along the x-axis, is approximately proportional to -
A
X
B
x2
C
x3
D
1/x
Answer
x2
Explanation
Solution
\ Ui = 
if charge is displaced Uf = 
+ 
DU = Uf – Ui = Kqq' 
if x2 < < a2 \ DU µ x2