Electrostatics Question 342
Question: Two spheres $ A $ and $ B $ of radius $ 4cm $ and $ 6cm $ are given charges of $ 80\mu c $ and $ 40\mu c $ respectively. If they are connected by a fine wire, the amount of charge flowing from one to the other is [MP PET 1991]
Options:
A) $ 20\mu C $ from $ A $ to $ B $
B) $ 16\mu C $ from $ A $ to $ B $
C) $ 32\mu C $ from $ B $ to $ A $
D) $ 32\mu C $ from $ A $ to $ B $
Show Answer
Answer:
Correct Answer: D
Solution:
Total charge $ Q=80+40=120\mu C $ .
By using the formula $ Q _{1}’=Q[ \frac{r _{1}}{r _{1}+r _{2}} ] $ . New charge on sphere A is $ Q _{A}^{’}=Q[ \frac{r _{A}}{r _{A}+r _{B}} ] $
$ =120[ \frac{4}{4+6} ]=48\mu C $ .
Initially it was $ 80\mu C $ i.e., $ 32\mu C $ charge flows from A to B.
