NEETPhysicsElectrostatics
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The electric field lines are always perpendicular to an equipotential surface at every point. Reason (R): The work done in moving a test charge along an equipotential surface is zero, which implies that the component of the electric field along the surface must be zero. In the light of the above st
Options
- ABoth (A) and (R) are correct but (R) is not the correct explanation of (A)
- B(A) is correct but (R) is not correct
- CBoth (A) and (R) are correct and (R) is the correct explanation of (A)
- D(A) is not correct but (R) is correct
Correct answer
C. Both (A) and (R) are correct and (R) is the correct explanation of (A)
Step-by-step solution
Assertion (A) is a true statement because electric field lines are always normal to equipotential surfaces. Reason (R) is also a true statement. By definition, the potential difference between any two points on an equipotential surface is zero. Therefore, the work done in moving a test charge q on this surface is W = q V = 0 . Work done is also given by the line integral of the electric force: W = F d l = q E d l = 0 . This implies that E d l = E , dl = 0 . Since E and dl are non-zero, = 0 , which gives = 90^ . Thu