NEETPhysicsElectrostatics
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): For an electric dipole of finite length 2a , the electric potential at a distance r (where r > a ) on the axial line near the positive charge is strictly greater than 1 4 ₀ p r^2 . Reason (R): The exact electric potential at this point is proportional to 1 r^2 - a^2 , and since (r^2 - a^2) In the l
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A)
- C(A) is correct but (R) is not correct
- D(A) is not correct but (R) is correct
Correct answer
A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
Step-by-step solution
The exact electric potential at a distance r on the axial line of a dipole (closer to the positive charge) is given by: V = 1 4 ₀ p r^2 - a^2 The approximate electric potential for a short dipole is: V_ approx = 1 4 ₀ p r^2 Since the point is at a distance r > a , the denominator of the exact formula (r^2 - a^2) is strictly less than r^2 . Because the denominator is smaller, the overall fraction is larger. Therefore, V > V_ approx . Thus, Assertion (A) is correct. Reason (R) correctly states the mathematical relati