Questions in Moving Charges and Magnetism

Select	Question
	A helium nucleus makes a full rotation in a circle of radius 0.8 metre in two seconds. The value of the magnetic field B at the centre of the circle will be
	A solenoid of 1.5 metre length and 4.0 cm diameter posses 10 turn per cm. A current of 5 ampere is flowing through it. The magnetic induction at axis inside the solenoid is
	The magnetic induction at a point P which is distant 4 cm from a long current carrying wire is ${10^{ - 8}}\,Tesla$. The field of induction at a distance 12 cm from the same current would be
	The strength of the magnetic field at a point r near a long straight current carrying wire is B. The field at a distance $\frac{r}{2}$ will be
	Field at the centre of a circular coil of radius r, through which a current I flows is
	A current of 0.1 A circulates around a coil of 100 turns and having a radius equal to 5 cm. The magnetic field set up at the centre of the coil is $({\mu _0} = 4\pi \times {10^{ - 7}}\,weber/ampere - metre)$
	The magnetic field B with in the solenoid having n turns per metre length and carrying a current of i ampere is given by
	The magnetic induction at the centre O in the figure shown is
	Field inside a solenoid is
	In the figure, shown the magnetic induction at the centre of there arc due to the current in portion AB will be