Electrostatics Question 249
Question: 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 [IIT-JEE (Screening) 2002]
Options:
A) 10
B) $ 5\sqrt{2} $
C) $ 10\sqrt{2} $
D) 20
Show Answer
Answer:
Correct Answer: C
Solution:
Body moves along the parabolic path.
For vertical motion : By using v = u + at therefore $ v _{y}=0+\frac{QE}{m}.t=\frac{{{10}^{-6}}\times 10^{3}}{{{10}^{-3}}}\times 10=10m/\text{sec} $
For horizontal motion -It’s horizontal velocity remains the same i.e. after 10 sec, horizontal velocity of body vx = 10 m/sec. Velocity after 10 sec $ v=\sqrt{v _{x}^{2}+v _{y}^{2}} $
$ =10\sqrt{2}m/sec $
