A straight wire carrying a current of $12\; A$ is bent into a semi-circular arc of radius $2.0\; cm$ as shown in Figure $(a)$. Consider the magnetic field $B$ at the centre of the arc.
$(a)$ What is the magnetic field due to the straight segments?
$(b)$ In what way the contribution to $B$ from the semicircle differs from that of a circular loop and in what way does it resemble?
$(c)$ Would your answer be different if the wire were bent into a semi-circular arc of the same radius but in the opposite way as shown in Figure $(b)$
$(a)$ $dl$ and $r$ for each element of the straight segments are parallel. Therefore, $d l \times r =0 .$ Straight segments do not contribute to $| B |$
$(b)$ For all segments of the semicircular arc, $d l \times r$ are all parallel to each other (into the plane of the paper). All such contributions add up in magnitude. Hence direction of $B$ for a semicircular arc
is given by the right-hand rule and magnitude is half that of a circular loop. Thus $B$ is $1.9 \times 10^{-4} T$ normal to the plane of the paper going into it.
$(c)$ Same magnitude of $B$ but opposite in direction to that in $(b).$
An $\alpha$ particle is moving along a circle of radius $R$ with a constant angular velocity $\omega $. Point $A$ lies in the same plane at a distance $2R$ from the centre. Point $A$ records magnetic field produced by $\alpha$ particle. If the minimum time interval between two successive times at which $A$ records zero magnetic field is $‘t’,$ find the angular speed $\omega $, in terms of $t.$
Write equation of magnetic field on axis from centre which have distance equal to radius.
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
An electron moves in a circular orbit with a uniform speed $v$. It produces a magnetic field $B$ at the centre of the circle. The radius of the circle is proportional to
Which of the following statements regarding magnetic lines of force is correct?