Question

Assertion (A): Equal amount of positive and negative charges are distributed uniformly on two halves of a thin circular ring as shown in figure. The resultant electric field at the centre O of the ring is along OC.
Reason (R): It is so because the net potential at O is not zero. 

• A. If both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
• B. If both Assertion (A) and Reason (R) are true and Reason (R) is not the correct explanation of Assertion (A).
• C. If Assertion (A) is true but Reason (R) is false.
• D. If both Assertion (A) and Reason (R) are false.

Hint:

In electrostatics, the electric field due to symmetrically placed charges is directed along the symmetry axis. The potential, however, is scalar and adds algebraically, so for a system with symmetrical charge distribution, the net potential can be zero even when the electric field is not.

Answer 1

The Correct Option is A

In this scenario, the charges are positioned symmetrically on both halves of the ring. Consequently, their electric fields at the center will nullify each other in directions orthogonal to the line connecting the charges. Therefore, the net electric field at point O lies along the axis OC, as the symmetry of the charge distribution guarantees a non-zero field in this specific direction.
Conversely, the total electric potential at O is indeed zero. This is attributable to the potential generated by the positive charges and negative charges at the ring's center canceling each other out symmetrically, resulting in a net potential of zero at O. Hence, the justification provided in (R) is inaccurate.
Consequently, the assertion (A) is accurate, while the reason (R) is false.