A straight wire is first bent into a circle of radius `r` and then into a square of side ` x` each of one turn. If currents flowing through them are in the ratio `4:5`. The ratio of their effective magnetic moments is -

Two identical wires A and B , each of length 'l', carry the same current I . Wire A is bent into a circle of radius R and wire B is bent to form a square of side 'a' . If B_(A) and B_(B) are the values of magnetic field at the centres of the circle and square respectively , then the ratio (B_(A))/(B_(B)) is :

Two identical wires A and B , each of length 'l', carry the same current I . Wire A is bent into a circle of radius R and wire B is bent to form a square of side 'a' . If B_(A) and B_(B) are the values of magnetic field at the centres of the circle and square respectively , then the ratio (B_(A))/(B_(B)) is :

A circular loop and a square loop are formed from the same wire and the same current is passed through them . Find the ratio of their dipole moments.

Two wires A and B are of lengths 40 cm and 30 cm. A is bent into a circle of radius r and B into an arc of radius r. A current i_(1) is passed through A and i_(2) through B. To have the same magnetic induction at the centre, the ratio of i_(1) : i_(2) is

A wire is bent in the form of a circular arc of radius r with a straight portion AB. If the current in the wire is i , then the magnetic induction at point O is

A wire of length l is cut into two parts. One part is bent into a circle and the other into a square. Prove that the sum of the areas of the circle and the square is the least, if the radius of the circle is half of the side of the square.

A part of a long wire carrying a current i is bent into a circle of radius r as shown in figure. The net magnetic field at the centre O of the circular loop is :

A part of a long wire carrying a current i is bent into a circle of radius r as shown in figure. The net magnetic field at the centre O of the circular loop is

A wire of length l is bent in the form a circular coil of some turns. A current I flows through the coil. The coil is placed in a uniform magnetic field B. The maximum torqur on the coil can be

One of the two identical conducting wires of length L is bent in the form of a circular loop and the other one into a circular coil of N identical turns. If the same current passed in both, the ratio of the magnetic field at the central of the loop (B_(L)) to that at the central of the coil (B_(C)) , i.e. (B_(L))/(B_(C)) will be :