Electrostatics Question 750
Question: Four identical particles each of mass m and charge q are kept at the four comers of a square of length L. The final velocity of these particles after setting them free will be
Options:
A) $ {{[ \frac{Kq^{2}}{mL}( 5.4 ) ]}^{1/2}} $
B) $ {{[ \frac{Kq^{2}}{mL}( 1.35 ) ]}^{1/2}} $
C) $ {{[ \frac{Kq^{2}}{mL}( 2.7 ) ]}^{1/2}} $
D) None of these
Show Answer
Answer:
Correct Answer: C
Solution:
[c] Potential energy of the system
$ 4\times \frac{K}{2}( \frac{q^{2}}{L}+\frac{q^{2}}{L}+\frac{q^{2}}{L\sqrt{2}} )=5.4\frac{Kq^{2}}{L} $
= Final kinetic energy of the system = $ 4\times \frac{1}{2}mv^{2}=2mv^{2} $
$ \therefore v={{[ \frac{Kq^{2}}{mL}( 2.7 ) ]}^{1/2}} $
