Electrostatics Question 735
Question: A disc of radius a/4 having a uniformly distributed charge 6C is placed in the x-y plane with its center at (-a/2, 0, 0). A rod of length a carrying a uniformly distributed charge 8C is placed on the x-axis from $ x=a/4 $ to $ x=5a/4 $ . Two point charges -7C and 3C are placed at (a/4, -a/4, 0) and (-3a/4, 3a/4, 0), respectively. Consider a cubical surface formed by six surfaces $ x=\pm a/2,y=\pm a/2,z=\pm a/2. $ The electric flux through this cubical surface is
Options:
A) $ \frac{-2C}{{\varepsilon _{0}}} $
B) $ \frac{2C}{{\varepsilon _{0}}} $
C) $ \frac{10C}{{\varepsilon _{0}}} $
D) $ \frac{12C}{{\varepsilon _{0}}} $
Show Answer
Answer:
Correct Answer: A
Solution:
[a] It is clear that the charge enclosed in the cubical surface is $ 3C+2C-7C=-2C. $
therefore the electric flux through the cube is $ \phi =\frac{q _{in}}{{\varepsilon _{0}}}=\frac{-2C}{{\varepsilon _{0}}} $
