Question

A toroidal coil has 3000 turns. The inner and outer radii are 10 cm and 14 cm respectively. If current flowing is 5A, then the magnetic field inside the toroid will be.

• A. $2.5\times {10}^{-5}T$
• B. $2.5\times {10}^{-2}T$
• C. $0.25T$
• D. $2.5\times {10}^{-4}T$

Answer 1

The correct option is B $2.5\times {10}^{-2}T$

Given,

$N=3000$

$R_i=10cm=0.10m$

$R_o=14cm=0.14m$

$R=\frac{R_i+R_o}{2}=0.12m$

$I=5A$

${\mu }_0=4\pi \times {10}^{-7}Tm{A}^{-1}$

The magnetic field inside the toroid will be

$B=\frac{{\mu }_{0}NI}{2\pi R}$

$B=\frac{4\pi \times {10}^{-7}\times 3000\times 5}{2\pi \times 0.12}$

$B=2.5\times {10}^{-2}T$

The correct option is B.