Assertion ( A ): A dc potentiometer measures the true open circuit emf of a source.
Reason ( R ): At balance point, a dc potentiometer does not draw any current from the source.
A. Both A and R are true and R is correct explanation of A
B. Both A and R are true but R is not correct explanation of A
C. A is true R is false
D. A is false R is true
Share your understanding of this question with the correct explanation.