Electrostatics Question 259
Question: Two point charges $ (+Q) $ and $ (-2Q) $ are fixed on the X-axis at positions $ a $ and $ 2a $ from origin respectively. At what positions on the axis, the resultant electric field is zero [MP PET 2001]
Options:
A) E at all points on the $ Y- $ axis is along $ \hat{i} $
B) The electric field $ \overrightarrow{E} $ at all points on the $ X- $ axis has the same direction
C) Dipole moment is $ 2qd $ directed along $ \hat{i} $
D) Work has to be done in bringing a test charge from infinity to the origin
Show Answer
Answer:
Correct Answer: A
Solution:
It is clear that $ \overrightarrow{E} $ at all points on the y-axis is along $ \hat{i} $ .
Here $ \overrightarrow{E} $ of all points on x-axis cannot have the same direction.
Here electric potential at origin is zero so no work is done in bringing a test charge from infinity to origin. Here dipole moment is in ? x direction (-q to +q).
Hence only option (a) is correct.
