A coil having $N$ $turns$ is wound tightly in the form of a spiral with inner and outer radii $a$ and $b$ respectively. When a current $I$ passes through the coil, the magnetic field at the centre is

  • [IIT 2001]
  • A

    $\frac{{{\mu _0}NI}}{b}$

  • B

    $\frac{{2{\mu _0}NI}}{a}$

  • C

    $\frac{{{\mu _0}NI}}{{2(b - a)}}\ln \frac{b}{a}$

  • D

    $\frac{{{\mu _0}{I^N}}}{{2(b - a)}}\ln \frac{b}{a}$

Similar Questions

A length $L$ of wire carries a steady current $I$. It is bent first to form a circular plane coil of one turn. The same length is now bent more sharply to give a double loop of smaller radius. The magnetic field at the centre caused by the same current is

  • [AIIMS 1980]

A hollow cylinder having infinite length and carrying uniform current per unit length $\lambda$ along the circumference as shown. Magnetic field inside the cylinder is

A coil having ${N}$ turns is wound tightly in the form of a spiral with inner and outer radii $'a'$ and $'b'$ respectively. Find the magnetic field at centre, when a current $I$ passes through coil :

  • [JEE MAIN 2021]

Apply Biot-Savart law to find the magnetic field due to a circular current carrying loop at a point on the axis of the loop.

Biot-Savart, law indicates that the moving electrons (velocity $v$) produce a magnetic  field $B$ such that