A battery is connected between two points $A$ and $B$ on the circumference of a uniform conducting ring of radius $r$ and resistance $R$. One of the arcs $AB$ of the ring subtends an angle $\theta $ at the centre. The value of the magnetic induction at the centre due to the current in the ring is
Proportional to $2\,(180^\circ - \theta )$
Inversely proportional to $r$
Zero, only if $\theta = 180^\circ $
Zero for all values of $\theta $
The resistances of three parts of a circular loop are as shown in the figure. The magnetic field at the centre $O$ is :-
A current $i$ ampere flows in a circular arc of wire whose radius is $R$, which subtend an angle $3\pi /2$ radian at its centre. The magnetic induction at the centre is
.......$A$ should be the current in a circular coil of radius $5\,cm$ to annul ${B_H} = 5 \times {10^{ - 5}}\,T$
An electron revolves around nucleus with rotational frequency $'f'$ in circular orbit, due to this magnetic induction produced at nucleus position is $'B'$ then radius of circular orbit is directly proportional to
An arc of a circle of radius $R$ subtends an angle $\frac{\pi }{2}$ at the centre. It carries a current $i$. The magnetic field at the centre will be