Questions in Moving Charges and Magnetism

Select	Question
	In a current carrying long solenoid, the field produced does not depend upon
	The earth's magnetic induction at a certain point is $7 \times {10^{ - 5}}Wb/{m^2}.$ This is to be annulled by the magnetic induction at the centre of a circular conducting loop of radius $5 cm$. The required current in the loop is
	Magnetic field due to 0.1 A current flowing through a circular coil of radius 0.1 m and 1000 turns at the centre of the coil is
	Magnetic field intensity at the centre of coil of 50 turns, radius 0.5 m and carrying a current of 2 A is
	A circular coil $A$ has a radius $R$ and the current flowing through it is $I$. Another circular coil $B$ has a radius $2R$ and if $2I$ is the current flowing through it, then the magnetic fields at the centre of the circular coil are in the ratio of (i.e.${B_A}$ to ${B_B}$)
	The magnetic field at a distance $r$ from a long wire carrying current $i$ is $0.4$ Tesla. The magnetic field at a distance $2r$ is
	A current $I$ flows along the length of an infinitely long, straight and thin-walled pipe. Then
	The magnetic field at the centre of current carrying coil is
	A straight wire of diameter 0.5 mm carrying a current of 1 A is replaced by another wire of 1 mm diameter carrying the same current. The strength of magnetic field far away is
	A neutral point is obtained at the centre of a vertical circular coil carrying current. The angle between the plane of the coil and the magnetic meridian is