A square loop is carrying a steady current $I$ and the magnitude of its magnetic dipole moment is $m$. If this square loop is changed to a circular loop and it carries the same current, the magnitude of the magnetic dipole moment of circular loop will be
JEE MAIN 2019, Medium
Download our app for free and get startedPlay store
$m = I{l^2}$         $2\pi r = 4l$

${{{\text{m}}^\prime } = \frac{{I4{\ell ^2}}}{\pi }}$      ${{\text{r}} = \frac{{2\ell }}{\pi }}$

${{{\text{m}}^\prime } = \frac{{I4{\ell ^2}}}{\pi }}$      ${\pi {r^2} = \frac{{\pi 4{\ell ^2}}}{{{\pi ^2}}} = \frac{{4{\ell ^2}}}{\pi }}$  

${{{\text{m}}^\prime } = \frac{4}{\pi }\,{\text{m}}}$

art

Download our app
and get started for free

Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*

Similar Questions

  • 1
    An electron gun is placed inside a long solenoid of radius $\mathrm{R}$ on its axis. The solenoid has $\mathrm{n}$ turns/length and carries a current $I$. The electron gun shoots an electron along the radius of the solenoid with speed $v$. If the electron does not hit the surface of the solenoid, maximum possible value of ${v}$ is (all symbols have their standard meaning)
    View Solution
  • 2
    Two ions of masses $4 \,{amu}$ and $16\, amu$ have charges $+2 {e}$ and $+3 {e}$ respectively. These ions pass through the region of constant perpendicular magnetic field. The kinetic energy of both ions is same. Then :
    View Solution
  • 3
    A uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an electron is projected in the region such that its velocity is pointed along the direction of fields, then the electron
    View Solution
  • 4
    A conductor in the form of a right angle $ABC$ with $AB = 3\, cm$ and $BC = 4\, cm$ carries a current of $10\, A$. There is a uniform magnetic field of $5\, T$ perpendicular to the plane of the conductor. The force on the conductor will be......$N$
    View Solution
  • 5
    A moving coil galvanometer, having a resistance $G$, produces full scale deflection when a current $I_g$ flows through it. This galvanometer can be converted into $(i)$ an ammeter of range $0$ to $I_0 (I_0 > I_g)$ by connecting a shunt resistance $R_A$ to it and $(ii)$ into a voltmeter of range $0$ to $V(V = GI_0)$ by connecting a series resistance $R_V$ to it. Then,
    View Solution
  • 6
    A proton, an electron, and a Helium nucleus, have the same energy. They are in circular orbitals in a plane due to magnetic field perpendicular to the plane. Let $r_p, r_e$ and $r_{He}$ be their respective radii, then
    View Solution
  • 7
    A proton of mass $1.67 \times {10^{ - 27}}\,kg$ and charge $1.6 \times {10^{ - 19}}\,C$ is projected with a speed of $2 \times {10^6}\,m/s$ at an angle of $60^\circ $ to the $X - $ axis. If a uniform magnetic field of $0.104$ $Tesla$ is applied along $Y - $ axis, the path of proton is
    View Solution
  • 8
    Two thick wires and two thin wires, all of the same materials and same length form a square in the three different ways $P$, $Q$ and $R$ as shown in fig with current connection shown, the magnetic field at the centre of the square is zero in cases
    View Solution
  • 9
    A proton is accelerating in a cyclotron where the applied magnetic field is $2 \,T$. If the potential gap is effectively $100 \,kV$ then how much revolutions the proton has to make between the "dees" to acquire a kinetic energy of $20 \,MeV$ ?
    View Solution
  • 10
    Two particles $x$ and $y$ have equal charges and possessing equal kinetic energy enter in a uniform magnetic field and describe circular path of radius of curvature $r_1$ and $r_2$ respectively. The ratio of their masses is
    View Solution