Solved: PHYSICS Question for NEET

NEET PHYSICSMedium

Select the correct option based on the statements: Statement I: The magnetic field of a circular loop at very far away point on the axial line varies with distance as like that of a magnetic dipole. Statement II: The magnetic field due to magnetic dipole varies inversely with the square of the distance from the centre on the axial line.

Statement I is correct and Statement II is incorrect.

Statement I is incorrect and Statement II is correct.

Both Statement I and Statement II are correct.

Both Statement I and Statement II are incorrect.

Step-by-Step Solution

Statement I Analysis: The magnetic field $B$ on the axis of a circular current loop of radius $R$ at a distance $x$ from the centre (where $x \gg R$ ) is given by the approximation: $B \approx \frac{\mu_0 I R^2}{2x^3}$ Substituting the magnetic moment $m = I(\pi R^2)$ , we get: $B \approx \frac{\mu_0 m}{2\pi x^3}$ This shows the field varies as $1/x^3$ , which is the characteristic behavior of a magnetic dipole. Thus, Statement I is correct.
Statement II Analysis: The magnetic field due to a magnetic dipole (or bar magnet) on the axial line at distance $r$ is given by: $B_{\text{axial}} = \frac{\mu_0}{4\pi} \frac{2m}{r^3}$ This indicates that the field varies inversely with the cube of the distance ( $1/r^3$ ), not the square ( $1/r^2$ ). Inverse square dependence applies to electric monopoles (point charges), not dipoles. Thus, Statement II is incorrect.

Practice Mode Available

Master this Topic on Sushrut

Join thousands of students and practice with AI-generated mock tests.

Get Started