A wire in the form of a circular loop of one turn carrying a current produces a magnetic field $B$ at the centre. If the same wire is looped into a coil of two turns and carries the same current, the new value of magnetic induction at the centre is

  • [AIPMT 2002]
  • A

    $5B$

  • B

    $3B$

  • C

    $2B$

  • D

    $4B$

Similar Questions

A current loop $ABCD$ is held fixed on the plane of the paper as shown in the figure. The arcs $ BC$ (radius $= b$) and $DA $ (radius $= a$) of the loop are joined by two straight wires $AB $  and $CD$. A steady current $I$ is flowing in the loop. Angle made by $AB$ and $CD$ at the origin $O$ is $30^o $. Another straight thin wire with steady current $I_1$ flowing out of the plane of the paper is kept at the origin.

Due to the presence of the current $I_1$ at the origin

  • [AIEEE 2009]

Two very thin metallic wires placed along $X$ and $Y$-axis carry equal currents as shown here. $AB$ and $CD$ are lines at $45^\circ $ with the axes with origin of axes at $O$. The magnetic field will be zero on the line

  • [AIPMT 1996]

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

  • [AIPMT 1997]

Consider two thin identical conducting wires covered with very thin insulating material. One of the wires is bent into a loop and produces magnetic field $B_1,$ at its centre when a current $I$ passes through it.The second wire is bent into a coil with  three identical loops adjacent to each other and produces magnetic field $B_2$ at the centre of the loops when current $I/3$ passes through it. The ratio $B_1 : B_2$ is

  • [JEE MAIN 2014]

The magnetic field at the centre of a circular coil of radius $r$ is $\pi $ times that due to a long straight wire at a distance $r$ from it, for equal currents. Figure here shows three cases : in all cases the circular part has radius $r$ and straight ones are infinitely long. For same current the $B$ field at the centre $P$ in cases $1$, $2$, $ 3$ have the ratio