In the light of the above statements, choose the correct answer from the options given below:
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true and R is NOT the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Answer
(3) A is true but R is false.
Solution
Potential at an axial point at distance r (for r dipole length):
V = 14 0 Pr2
= 9 109 4 10-622
= 9 103 V
(+ on the side of the positive charge, - on the side of the negative charge.) So A is true.
R gives V = 2P4 0 r2, which is the form of the axial electric field, not the potential. So R is false.
Answer: (3)