Q. An infinitely long current carrying wire and a small current carrying loop are in the plane of the paper as shown. The radius of the loop is a and distance of its centre from the wire is d (d > > a). If the loop applies a force F on the wire then :

Physics Question Image

Solution:

Eqvilent dipole of given loop
$F =m . \frac{dB}{dr} $
Now $ \frac{dB}{dx} = \frac{d}{dx} \left(\frac{\mu_{0}I}{2\pi x}\right) $
$ \propto\frac{1}{x^{2}} $
$ \Rightarrow \text{So} F \propto \frac{M}{x^{2}} \left[\because M = NIA\right] $
$ \therefore F \propto\frac{a^{2}}{d^{2}} $

Solition Image

You must select option to get answer and solution

Questions from JEE Main 2019

Physics Most Viewed Questions

8. The hot wire ammeter measures

Rajasthan PMT 2004 Alternating Current