Electrostatics Question 195
Question: Electric charges of $ 1\mu C,-1\mu C $ and $ 2\mu C $ are placed in air at the corners A, B and C respectively of an equilateral triangle ABC having length of each side 10 cm. The resultant force on the charge at C is [EAMCET (Engg.) 2000]
Options:
A) 0.9 N
B) 1.8 N
C) 2.7 N
D) 3.6 N
Show Answer
Answer:
Correct Answer: B
Solution:
FA = force on C due to charge placed at A
$ =9\times 10^{9}\times \frac{{{10}^{-6}}\times 2\times {{10}^{-6}}}{{{(10\times {{10}^{-2}})}^{2}}}=1.8N $
FB = force on C due to charge placed at B
$ =9\times 10^{9}\times \frac{{{10}^{-6}}\times 2\times {{10}^{-6}}}{{{(0.1)}^{2}}}=1.8N $
Net force on C $ F _{net}=\sqrt{{{(F _{A})}^{2}}+{{(F _{B})}^{2}}+2F _{A}F _{B}\cos 120^{o}}=1.8N $
