Electrostatics Question 256
Question: Two point charges $ +q $ and $ -q $ are held fixed at $ (-d,0) $ and $ (d,0) $ respectively of a $ (X,Y) $ coordinate system. Then [IIT 1995]
Options:
A) $ {{( \frac{g+\frac{qE}{m}}{g} )}^{1/2}} $
B) $ {{( \frac{g}{g+\frac{qE}{m}} )}^{3/2}} $
C) $ {{( \frac{g}{g+\frac{qE}{m}} )}^{1/2}} $
D) None of these
Show Answer
Answer:
Correct Answer: C
Solution:
Net downward force $ mg’=mg+QE $
therefore Effect acceleration $ g’=( g+\frac{QE}{m} ) $
Hence time period $ T=2\pi \sqrt{\frac{l}{g’}}=2\pi \sqrt{\frac{l}{( g+\frac{QE}{m} )}} $
