# Calculated the magnetic moment (in ) of a thin wire with a current  A, wound tightly on a half a tore (see figure). The diameter of the cross section of the tore is equal to  cm, and the number of turns is

## Question ID - 153953 | SaraNextGen Top Answer Calculated the magnetic moment (in ) of a thin wire with a current  A, wound tightly on a half a tore (see figure). The diameter of the cross section of the tore is equal to  cm, and the number of turns is

Answer Key / Explanation : (5) -

(5)

The magnetic moment of circular current is given by  being the circulating current and  is the area of cross-section; the direction is perpendicular to the plane of current. Now, for an element of toroid of length , its magnetic moment is along the direction of arrow as shown, of magnitude (perpendicular to its cross-section)=current  area  number of turns in the length

Resolving dM into components along  and , we get  and ; components along  from neighbouring elements cancel out to zero, and components along  are added. So

Putting the given values we get