Question

If \(Q\) is the magnitude of charge and \(r\) is the distance between the centres of positive and negative charges, then dipole moment (\(\mu\)) is given by

• A. \(\mu = Q + r\)
• B. \(\mu = Q \times r\)
• C. \(\mu = \dfrac{Q}{r}\)
• D. \(\mu = Q - r\)

Hint:

Dipole moment increases with increase in either charge magnitude or distance between the charges.

Answer 1

The Correct Option is B

Step 1: Understanding dipole moment.
Dipole moment is a vector quantity that represents the separation of positive and negative charges in a molecule. It depends on the magnitude of charge and the distance between the charges.

Step 2: Mathematical expression.
For a dipole consisting of charges \(+Q\) and \(-Q\) separated by a distance \(r\), the dipole moment is defined as: \[ \mu = Q \times r \]

Step 3: Analysis of options.
(A) Incorrect — dipole moment is not a sum of charge and distance.
(B) Correct — dipole moment is the product of charge and separation distance.
(C) Incorrect — inverse relation is not applicable.
(D) Incorrect — subtraction has no physical meaning here.

Step 4: Conclusion.
The correct expression for dipole moment is \(\mu = Q \times r\).