Questions in Moving Charges and Magnetism

Select	Question
	Two long straight wires are set parallel to each other. Each carries a current i in the same direction and the separation between them is 2r. The intensity of the magnetic field midway between them is
	A magnetic field can be produced by
	Unit of magnetic permeability is
	A long straight wire carries a current of $\pi \,amp.$ The magnetic field due to it will be $5 \times {10^{ - 5}}{\rm{ }}weber/{m^{\rm{2}}}$ at what distance from the wire $[{\mu _o} = $permeability of air]
	When a certain length of wire is turned into one circular loop, the magnetic induction at the centre of coil due to some current flowing is ${B_1}$ If the same wire is turned into three loops to make a circular coil, the magnetic induction at the center of this coil for the same current will be
	Gauss is unit of which quantity
	On connecting a battery to the two corners of a diagonal of a square conductor frame of side $a$ the magnitude of the magnetic field at the centre will be
	The ratio of the magnetic field at the centre of a current carrying coil of the radius a and at a distance ‘a’ from centre of the coil and perpendicular to the axis of coil 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 centreO of the circular loop is
	The current in the windings on a toroid is $2.0A$. There are 400 turns and the mean circumferential length is 40 cm. If the inside magnetic field is 1.0T, the relative permeability is near to